The Map of Hogwarts: Hogwarts Castle

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Location
Setting
The school grounds
Hogsmeade
The Forbidden Forest
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The Map of Hogwarts and Surrounding Areas:
Hogwarts Castle

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Analysis
General appearance
Basic layout

Conclusion
Criteria which must be met
Plan of Hogwarts castle

Any attempt to work out the groundplan of Hogwarts castle can only be an approximation. The freely-rotating, hanging-in-space staircases we see on-screen There were a hundred and forty-two staircases at Hogwarts: wide, sweeping ones; narrow, rickety ones; some that led somewhere different on a Friday; some with a vanishing step halfway up that you had to remember to jump. Then there were doors that wouldn't open unless you asked politely, or tickled them in exactly the right place, and doors that weren't really doors at all, but solid walls just pretending. It was also very hard to remember where anything was, because it all seemed to move around a lot. [PS ch. #08; p. 98]

'You can't come down here!' Ginny was calling to the crowd. 'No, sorry, you're going to have to go round by the swivelling staircase, someone's let off Garrotting Gas just along here --' [OotP ch. #32; p. 651] are (like animated Chocolate Frogs!) largely an invention by Warner Bros., but a single "swivelling stair" is indeed mentioned, and at least two stairs which go to different places according to the day of the week, and it's canon that bits of Hogwarts do move around. Indeed, JK Rowling herself has said that she doesn't have a map of the castle, for that very reason. Ms. Rowling, have you ever made a map or blueprint of the school?
No, because all those staircases keep shifting around and rooms pop out of nowhere, and stuff just moves too much. But I have got a notebook that reminds me what floor everything is on, just to keep track. Of course, if anything moves, I can blame it on magic, not my mistakes. [America Online chat transcript, AOL.com, 19^th October 2000]

Nevertheless, the staff and students generally do find their way from point to point, so the movement can't be random. There must be areas that don't move; or the moving bits must have a limited number of possible locations; or they must move only occasionally, and stay in one place for long enough for people to adjust to it. Or perhaps places stay the same but the access routes change. The Fat Lady seems to be sometimes on the seventh and sometimes on the third floor - but perhaps she is always in the same place, and the corridor that leads to her sometimes jumps four floors up or down whilst appearing to be level.

Better still, perhaps the reason people sometimes go downstairs to get to things which should be on a floor higher than their starting point, and vice versa, is because some of the stairs are Escher Specials which you walk down to go up and up to go down.

Another problem is that although there are certain fixed points - such as that the Astronomy Tower is next to the main doors, and Gryffindor Tower overlooks the beech tree by the lake - there are probably many ways of reconstructing the castle which would work. No plan of Hogwarts can be definitive, therefore: but what follows is, at any rate, one working possibility. I have tried, as far as possible, to preserve the idea shown in JK Rowling's own map, of the castle as a central block between two side-pieces.

Images from Wikipedia/Wikimedia and from Geograph are used and licensed for reuse under the Creative Commons Licence.

What we know or can deduce about the layout of the castle:

General appearance

What can we expect Hogwarts castle to look like? Probably not a whole lot like the Warner Brothers' version of the castle seen in the films.

The "candle-snuffer" tops which Warners have given to the towers of Hogwarts did occur in the Middle Ages. A good example of a French castle with conical roofs is the twelfth century, and now lost, Temple de Paris, and they are also found on French chateaux such as that at Saint-Fargeau. They were very occasionally found in British castles,

for example at Orford castle (in this case the conical roof no longer exists but it can be seen in reconstructions): but they were much more typically continental. Castles and Ancient Monuments in Great Britain says e.g. "French castle towers also had conical roofs, but this was never common in England where they usually had flat tops."

'OK, Buckbeak, up!' said Harry, shaking the rope. 'Up to the tower – come on!'
The Hippogriff gave one sweep of its mighty wings and they were soaring upwards again, high as the top of the West Tower. Buckbeak landed with a clatter on the battlements and Harry and Hermione slid off him at once. [PoA ch. #21; p. 303]

Indeed, we can see that the West Tower definitely has a flat top and battlements, in the standard English/Welsh style, because Harry lands Buckbeak on top of the tower. [This also slightly implies that the nearest bit of castle-block - the area of Flitwick's office - has a sloping roof they couldn't land on.]

Little ornamental turrets, some with candle-snuffer roofs, seem to have enjoyed a minor vogue in early seventeenth century Scotland, of which Craigievar Castle is an especially fine - or possibly demented - example, but they are most usually typical of the Queen Anne (early eighteenth century) and Queen Anne revival (late nineteenth century) periods.

We see them especially on "Scottish Baronial" buildings of the late Victorian Gothic revival, such as Torosay castle in Mull, or Balmoral; or on original castles which were rebuilt or substantially remodelled in the Victorian era, such as Castle Coch in Wales; but they are very uncommon as an original feature of Mediaeval British castles. Orford was the only example I could find.

The exterior of the film version of Hogwarts looks as if it was inspired by a cross between the Temple de Paris and Neuschwanstein castle in Bavaria, which was also used as the basis for the Sleeping Beauty castle at Disneyland. But pretty as they are, the Temple de Paris is very French, and Neuschwanstein was never a real, working castle at all: it's an overgrown nineteenth century folly designed by a stage-set designer to satisfy the Wagnerian fantasies of a king with mental health issues. Consequently, Hogwarts as envisaged by Warners doesn't look even vaguely like a genuine Mediaeval British castle: if it resembles any British building, it looks like a Victorian-Gothic railway station.

In fact, Hogwarts as envisioned by Warners bears a strong resemblance to the Victorian St Pancras building in London, comprising St Pancras Station and the former Midland Grand Hotel (now St Pancras Chambers). Of course, a wizards' castle won't necessarily look like a Muggle one, and Hogwarts could in any case have been re-modelled in the nineteenth century, like so many other Scottish castles. But St Pancras Station is only a few yards from King's Cross - the two stations are twinned - so Harry would have seen the St Pancras building in the morning of the day he first saw Hogwarts.

Harry, an English boy with, presumably, an English expectation of what a castle should look like, sees Hogwarts for the first time and immediately thinks of it as a castle, not as a massive Victorian-Gothic hotel or station or some kind of alien structure. So presumably it looks to him as he expects a castle to look, and not like the St Pancras station/hotel complex he'd seen that morning, and hence not like the Warners version of Hogwarts.

Many of the close-ups and interiors of Hogwarts are shot either at Christchurch College, Oxford or at Alnwick castle in Northumberland. Alnwick is a lot more suitable as a model for Hogwarts than Neuschwanstein - a real fortress, built over a Norman foundation and having some bits which date back to the early 14^th C. Most of it is more recent, however: it was extensively restored in the mid 16^th C (the windows are typical of that period) and substantially rebuilt in the 18^th C, after the original castle had become derelict. The interiors are Georgian "Strawberry Hill Gothick" and Victorian neo-Gothic revival - in many cases, consciously Italianate Victorian neo-Gothic - and overall what's there now is mostly cod-Mediaeval rather than authentic. They marched in silence around a corner and she stopped before a large and extremely ugly stone gargoyle.
'Sherbert lemon!' she said. This was evidently a password, because the gargoyle sprang suddenly to life and hopped aside as the wall behind him split in two. [CoS ch. #11; p. 152]

Harry and Ron packed away their unused ingredients and went to wash their hands and ladles in the stone basin in the corner.
'What did Malfoy mean?' Harry muttered to Ron, as he stuck his hands under the icy jet that poured from a gargoyle's mouth. [PoA ch. #07; p. 97]

Two stone gargoyles flanked the staff-room door. As Harry approached, one of them croaked, 'You should be in class, Sonny Jim.' [OotP ch. #17; p. 318]

Looking down, Harry saw Grawp the giant meandering past, swinging what looked like a stone gargoyle torn from the roof [DH ch. #31; p. 503]

Of course, it's possible that Hogwarts too has been extensively rebuilt and redecorated in an ornate, frilly Italianate Victorian-Gothic manner: but there's no evidence for this in the books. We do know that the castle has a lot of gargoyles, as well as detachable decorations such as portraits, tapestries, vases, suits of armour etc. but there's no indication of excessive curliques. We also have to consider what sort of thing JK Rowling probably had in mind when she first imagined Hogwarts.

So what would an authentic, early Mediaeval British castle look like?

If we discount Roman forts and the Iron Age brochs (round, open-topped stone towers) of Northern Scotland, the earliest British stone castle with a known, definite date is Chepstow castle, which JK Rowling must know well, since she went to school in Chepstow. It was begun in 1067AD, at which point it was called the castle of Striguil, from the Welsh ystraigyl, "bend in the river", and just over a century later it became the seat of William Marshal, widely regarded as the greatest English knight of the Middle Ages.

At the time that Chepstow castle was being built, and for some decades after, British castles were more usually made of wood and earthworks; so Chepstow was an innovation.         'You all know, of course, that Hogwarts was founded over a thousand years ago – the precise date is uncertain – by the four greatest witches and wizards of the age. [cut] They built this castle together [cut]
       [cut] 'For a few years, the founders worked in harmony together [cut] But then disagreements sprang up between them. [cut] Slytherin left the school.'[cut]
       [cut] 'The story goes that Slytherin had built a hidden chamber in the castle' [CoS ch. #09; p. 114]

        'It matters,' said Hermione, speaking at last in a hushed voice, 'because being able to talk to snakes was what Salazar Slytherin was famous for. That's why the symbol of Slytherin house is a serpent.'
       Harry's mouth fell open.
       'Exactly,' said Ron. 'And now the whole school's going to think you're his great-great-great-great-grandson or something ...'
       'But I'm not,' said Harry, with a panic he couldn't quite explain.
       'You'll find that hard to prove,' said Hermione. 'He lived about a thousand years ago; for all we know, you could be.' [CoS ch. #11; p. 147]

[cut] a statue high as the Chamber itself loomed into view, standing against the back wall.
Harry had to crane his neck to look up into the giant face above: it was ancient and monkey-like [CoS ch. #17; p. 226]

'Speak to me, Slytherin, greatest of the Hogwarts Four.' [cut]
Slytherin's gigantic stone face was moving [CoS ch. #17; p. 234]

       A thousand years or more ago,
       When I was newly sewn,
       There lived four wizards of renown,
        Whose names are still well known:
       Bold Gryffindor, from wild moor,
       Fair Ravenclaw, from glen,
       Sweet Hufflepuff, from valley broad,
       Shrewd Slytherin, from fen.
       They shared a wish, a hope, a dream,
       They hatched a daring plan
       To educate young sorcerers
       Thus Hogwarts School began. [GoF ch. #12; p. 156/157]

       So Hogwarts worked in harmony
       For several happy years,
       But then discord crept among us
       Feeding on our faults and fears.
       The houses that, like pillars four,
       Had once held up our school,
       Now turned upon each other and,
       Divided, sought to rule.
       And for a while it seemed the school
       Must meet an early end,
       What with duelling and with fighting
       And the clash of friend on friend
       And at last there came a morning
       When old Slytherin departed [OotP ch. #11 p. 186] In autumn 1992 Professor Binns tells the class that Hogwarts was founded "over a thousand years ago", so it was begun prior to 992AD, and there are other references to the Founders coming together and starting the school in the late nine-hundreds. If the Founders indeed built the castle in the mid to late tenth century, then that's about a hundred years before Mediaeval stone castles began to be built by Muggles in Britain - but we do not know whether they actually started from scratch with a stone building, or whether the earliest version of Hogwarts was something more in-period.

If so, the school may initially just have been held in ordinary houses in the village. If there was a designated school building there a century before Chepstow castle was built, then most likely it was either a broch or a wooden structure, replaced with a classic stone castle probably in the late eleventh or early twelfth century, and then added to over the years. If Hogwarts is in the Highlands of Scotland, then the earliest school building might actually have been a traditional "black house" - a long, low building with thick drystone walls, and turf growing over the roof.

We know that the Founders were old enough to be "wizards of renown" when they came together to build the school, but there's no mention of them already being elderly at that point. We are told that the four built the castle together, and that after "a few years" or "several happy years" there was a quarrel which resulted in Slytherin leaving the school, although we do not know how long a time elapsed between the start of the quarrel and Salazar leaving.

Prior to his departure, Slytherin had built a secret chamber within the castle. Judging from the statue in the Chamber of Secrets, which both Harry and Tom believe to be of Salazar Slytherin, Salazar was already very old when he built the Chamber, or at least when the statue was installed - and the Chamber is in the foundations of the castle and may well have been put in whilst it was first being built. That gives us at least some reason to think that by the time the stone castle was being built, Salazar was a very old man.

Depending on how far we can stretch the period of planning the school and then the "several happy years" during which it worked well, then, we may be able to move the founding of the stone castle forwards into the same time-frame as Chepstow. You can imagine that Salazar might have been fifty when the school was first begun in a pre-Norman-style building, and a hundred and fifty (or more) when he left it, a few years after work was begun on the stone castle in circa 1070AD.

Also, although Binns says that the Founders built the castle, he's a poor teacher and may not be accurate. The fact that the castle has dungeons - in the sense of underground chambers, not the original meaning of a "donjon" or castle keep - and an entire wing for medical treatment tends to suggest it was built as a proper military castle, perhaps even a Muggle one, which the school annexed. Perhaps the school was originally housed in outbuildings or in one wing of the castle, under the patronage of the lord who owned it - whether magical or Muggle - and gradually the school edged out the military aspect of the building.

Or perhaps the Founders built it for a local laird as a shared project: "We will build you a great fortress, my lord, so long as you let us have our school in part of it and your soldiers protect us." You certainly wouldn't think they would need such a vast castle just for a school at a time when the entire population of Britain was about 1.5 million. The total number of witches and wizards in Britain, if the proportions were the same then as they are today (see essay on population figures), should have been around two hundred and fifty; and that early in the school's history it's unlikely that more than half the eligible children attended. Even if they took children from age seven, and allowing for shorter lifespans and a higher proportion of young people, there can't have been more than forty or fifty students at that time, unless they recruited on the continent as well. The "houses" in the Founders' time must have been more like the Slug Club - a handful of favourite students gathered around one teacher - and they can't possibly have needed a building anything like the size of the one Hogwarts eventually ended up with.

Red Hen has suggested that the castle might originally have been some kind of central citadel for the wizarding world as a whole, not just a school.

Both the Ministry and St Mungo's in the books are based in/behind/under Muggle buildings which themselves were probably only built in about 1860. The Muggle area surrounding Diagon Alley was mainly open fields and market gardens until 1630 and didn't begin to become seriously built-up until more than a century later, which suggests that prior to about 1750 Hogsmeade may well have been the only major wizarding shopping centre in mainland Britain. The Famous Wizard Cards do place the building of The Leaky Cauldron around 1500 and have Diagon Alley already extant at that time. Before the area was a convent garden it had been the heart of Saxon London up to around 900, so it's possible Diagon alley was established early and then hidden from Muggle eyes - but it must have been pretty small at that time. Daisy Dodderidge
Tavern Keeper
1467 - 1555
Daisy Dodderidge built the Leaky Cauldron inn to serve as a gateway between the non-wizarding world and Diagon Alley. Wizards and witches of her day loved her generosity and the welcoming atmosphere of her pub. [Famous Wizard Cards]

Mungo Bonham
1560 - 1659
Famous wizard healer. Founded Saint Mungo's Hospital for Magical Ailments and Injuries. [Famous Wizard Cards]

Again according to the Famous Wizard Cards, St Mungo's was founded around 1600, although we're not told where. Certainly not in the building it's in in Harry's time, and probably not on that spot. It would certainly make a lot of sense if St Mungo's (which must be a teaching hospital, since it seems to be the only British wizarding hospital there is, and healers have to learn somewhere) was originally based at Hogwarts, whether or not the wizarding government was also once housed there. It would explain both why St Mungo's is named for a saint famously associated with the west coast of Scotland, and why Hogwarts has an entire wing devoted to medical matters. Perhaps the hospital moved to London once the Diagon Alley complex outgrew Hogsmeade.

It is noteworthy that the school and village have related names, yet neither is actually named after the other - that is, the school isn't called Hogsmeade school, and the village isn't called e.g. Schola Magi or similar, as you would expect if the village had grown up around the school. Yet, the school is called after what seems to be a place name, and one linked to the name of the village. This suggests that Hogsmeade came first, and Hogwarts was built on the site of a pre-existing named location - another village, or a hamlet, farm, land-feature or house - whose name it inherited.

However, according to the Famous Wizard cards Hogsmeade village was founded by a wizard named Hengist of Woodcroft, and the earliest British village named Woodcroft seems to date back only to the 12th C, which suggests that Hogsmeade village is two hundred years younger than the castle. Most probably there was a croft or a "farmtoun" (a large, multi-family farm) there originally, and Hengist used this as the basis for a village.

Hogwarts is an exceedingly tall castle - eight storeys plus towers. [Note for US readers: the highest floor named is the seventh floor, but we call the floor at street-level the "ground floor", and our first floor is your second floor. Hence, our seventh floor is your eighth.] So far as I've been able to ascertain there are only two castles in Scotland which are that high: Borthwick, which is a socking-great plain brick of a thing dating from the fifteenth century, and Craigievar, which is an early seventeenth century confection covered with mad little add-on turrets.

Rowling may well have been inspired to make Hogwarts that tall as a result of living in Edinburgh. The original, oldest part of the city was constructed on a narrow ridge, bounded by a loch on either side, so the only way to go was up. Edinburgh invented the skyscraper - there were fourteen-storey tenements here in the sixteenth century. A few eleven- and twelve-storey blocks from that period still survive, and even nowadays most buildings in central Edinburgh are at least four storeys high, and many much higher. It affects your expectations of what constitutes a large building - even though in reality most castles would have only three or four storeys.

There are a few good Scottish examples, such as the one at Bothwell, of the classic "toy fort"-style Mediaeval castles so common in England and Wales, with a courtyard and keep surrounded by corner towers and high narrow curtain walls. But castles in Scotland are more typically either stand-alone fortified houses such as the Mediaeval Cardoness Castle or, more latterly, like Borthwick and Craigievar; or small villages of barracks and administrative buildings inside a fairly low perimeter wall, defended mainly by being sited on top of great big rocks, such as we see at Stirling and Edinburgh. There are also many large Victorian Scottish houses and hotels which call themselves "castles" solely on the strength of being large and having a few Victorian mock-Gothic turrets glued to the outside of a normal house.

JK Rowling's own map shows Hogwarts as a square central block with additional, smaller blocks at the sides. You could imagine that if Hogwarts is a Scottish-style castle it might have begun as a plain block like Borthwick which was magically enhanced when the Craigievar-style twiddly little turrets came into fashion.

However, the castle has to look like something which Harry, an English eleven-year-old who has almost certainly never been taken on holiday in Scotland, would look at and immediately think "castle". He might recognise a village-on-a-rock like Edinburgh or Stirling castles as a castle because Edinburgh castle is the site of the annual Edinburgh Military Tattoo, and as such is massively famous and often on the telly; but he probably wouldn't think of a plain fortified house as a castle. Hogwarts must be a bit more toy-fort-ish than that; more like the classic English or Welsh design.

The castles with which JKR herself is most familiar are probably Chepstow, Caldicot and Edinburgh castles. Of these, Chepstow and Caldicot castles must have been well known to her as a girl, since she went to school in Chepstow, and Caldicot is the next town along, only five miles from Chepstow. Edinburgh castle is certainly very familiar to her as an adult, since it dominates the skyline of the city where she lives.

Chepstow and Caldicot castles are both classic Welsh Norman-period castles, all grey stone walls and battlemented towers, begun in 1067AD and 1086AD respectively. Edinburgh castle is an equally classic Scots village-on-a-rock kind of castle.

Chepstow castle is over two hundred yards long (although narrow, being a sort of elongated teardrop shape) and stands, spectacularly, high above the banks of the River Wye, with water apparently flowing in through an entrance under the castle, like the tunnel which the first-years at Hogwarts sail into. Looking at photographs of Chepstow castle, it's easy to see what might have inspired Rowling with the idea of a castle one face of which stands on a cliff above a lake - or in Chepstow's case, a tidal river - while the side at right-angles to the cliff overlooks a sweep of steep green lawns leading down to bushes and, yes, what looks to be a beech tree at the edge of the water.

Edinburgh castle is even bigger - three hundred and fifty yards long (if you include the esplanade) and a hundred and fifty yards wide - and was also built high on a cliff above a loch. The loch was drained centuries ago to make Princes Street Gardens, but people in Edinburgh still remember it used to be there, and a surviving eighteenth century painting shows how it looked. Like Hogwarts, Edinburgh castle has been there on that rock in some form or another for over a thousand years. Midnight ticked nearer as they heaved Norbert up the marble staircase in the Entrance Hall and along the dark corridors. Up another staircase, then another - even one of Harry's shortcuts didn't make the work much easier.
        'Nearly there!' Harry panted as they reached the corridor beneath the tallest tower. [cut]
       The steep spiral staircase up to the top of the tower seemed the easiest thing in the world after that. [cut]
        The answer to that was waiting at the foot of the stairs. As they stepped into the corridor, [PS ch. #14; p. 175/176]

The journey through the castle to North Tower was a long one. Two years at Hogwarts hadn't taught them everything about the castle, and they had never been inside North Tower before.
       There's – got – to – be – a – short – cut,' Ron panted, as they climbed their seventh long staircase and emerged on an unfamiliar landing [cut]
       They hurried after [Sir Cadogan] along the corridor, following the sound of his armour. [cut]
       [cut] they saw him reappear in front of an alarmed group of women in crinolines, whose picture hung on the wall of a narrow spiral staircase.
       Puffing loudly, Harry, Ron and Hermione climbed the tightly spiralling steps [PoA ch. #06; p. 77/78]

       The Hippogriff gave one sweep of its mighty wings and they were soaring upwards again, high as the top of the West Tower. Buckbeak landed with a clatter on the battlements and Harry and Hermione slid off him at once. [cut]
       They slipped through the doorway behind them and down a tightly spiralling stone staircase. As they reached the bottom of it, they heard voices. They flattened themselves against the wall and listened. It sounded like Fudge and Snape. They were walking quickly along the corridor at the foot of the staircase. [cut]
       [cut] Harry and Hermione waited a few moments to make sure they'd really gone, then started to run in the opposite direction. Down one staircase, then another, along a new corridor [cut]
       They had reached the end of the corridor with the hospital wing entrance. [PoA ch. #22; p. 303-305]

        He leapt the last ten steps of the spiral staircase and stopped where he landed, his wand raised: the dimly lit corridor was full of dust; half the ceiling seemed to have ¦fallen in and a battle was raging before him, but even as he attempted to make out who was fighting whom, he heard the hated voice shout, 'It's over, time to go!' and saw Snape disappearing round the corner at the far end of the corridor; [cut]
       Harry scrambled up from the floor and began to sprint along the corridor, ignoring the bangs issuing from behind him, the yells of the others to come back, and the mute call of the figures on the ground, whose fate he did not yet know ...
       He skidded round the corner, his trainers slippery with blood; Snape had an immense head-start – was it possible that he had already entered the Cabinet in the Room of Requirement [cut]
       [cut] he saw the brother and sister Death Eaters running down the marble staircase ahead [cut]
       He pelted towards a short cut, hoping to overtake the brother and sister and close in on Snape and Malfoy, who must surely have reached the grounds by now; remembering to leap the vanishing step halfway down the concealed staircase he burst through a tapestry at the bottom and out into a corridor [HBP ch. #28; p. 557-561]

'Wha's tha', lyin' on the grass?' Hagrid added sharply, heading now towards the foot of the Astronomy Tower, where a small crowd was congregating. 'See it, Harry? Righ' at the foot o' the Tower? Under where the Mark ... blimey ... yeh don' think someone got thrown –?' [HBP ch. #29; p. 567]

[cut] for an instant he knelt again beside Dumbledore’s body at the foot of the tallest tower at Hogwarts [DH ch. #24; p. 386]

Yet, Hogwarts has a whiff of Craigievar about it too. It's one of the oddities of the books that whenever the characters enter a tower, they apparently do so from the seventh floor. It isn't just Gryffindor Tower and the Headmaster's office which have special entrances: whenever anyone enters a tower, and we are told how they do it, they do it from high up. For example, after Dumbledore's death, Harry follows Snape and the Death Eaters down the stair from the top of the Astronomy Tower and they emerge into a corridor where he thinks that Snape may be heading for the Room of Requirement - which from other evidence we know to be based on the seventh floor. Harry is certainly still high up, since he has to run downstairs in order to follow Snape out into the grounds. When Harry and Hermione climb down the West Tower after seeing Sirius and Buckbeak off they emerge into a corridor which is two levels above the entrance to the hospital wing - another point which is usually quite high up.

We know that at least some of the towers really are towers, proper - that is, they go all the way down to the ground - because the Astronomy Tower has a base at ground level, and so it may be that they simply enter the towers at a high level in order to avoid having to climb spiral stairs. Yet, so many of the towers are entered from a high point that it may well be Perched atop a high mountain on the other side, its windows sparkling in the starry sky, was a vast castle with many turrets and towers. [PS ch. #06; p. 83] that many of them are not towers but turrets, which really do mushroom out of the walls halfway up. We are certainly told, when Harry first catches sight of the castle, that it has both towers and turrets. It may also be that Rowling is vaguely thinking of these "towers" as if they actually sprang from the roof, like chimney-stacks - but a tower set like that would lose much of its defensive capability and we know, in any case, that the Astronomy Tower has a definite base at ground level and even so, they enter it from the seventh floor. Possibly the lower storeys of the towers are used for something private, such as house-elf quarters, or the sections of the tower which correspond with the floors of the main building have been opened up as offices. The painted image of Phineas Nigellus Black was able to flit between his portrait in Grimmauld Place and the one that hung in the Headmaster’s office at Hogwarts: the circular tower-top room where Snape was no doubt sitting right now, [DH ch. #12; p. 188]

It's probably safe to assume that the ones which actually have "Tower" in their name - the Gryffindor, Ravenclaw, North, West and Astronomy Towers - really are towers: that is, they go all the way to the ground. Harry at one point thinks vaguely that the Headmaster's office is in a tower, but it's never formally called the Something-Tower, and since Harry may well not know the difference between a tower and a turret, it's possible that the Head's office is in a turret. For further information on and pictures of the castles shown:
Alnwick castle
Balmoral castle
Borthwick castle
Bothwell Castle
Caerlaverock Castle
Caldicot castle
Cardoness Castle
Chepstow castle
Castle Coch
Craigievar castle
Duncraig castle
Edinburgh castle
Eilean Donan castle
Mont Orgueil castle
Neuschwanstein castle
Orford castle and virtual reconstruction
Temple de Paris
Chateau Saint-Fargeau
Stirling castle
Torosay castle

I find it helps to visualise the many peculiarities of Hogwarts if you imagine it as a kind of hybrid between Chepstow, Edinburgh and Craigievar. The architectural style would be essentially Norman, as at Chepstow, literally towering above the water. That explains the facts - established in the section on the grounds of Hogwarts - that even though the castle stands on what is presumably a stone cliff, if you dig down under it you can tunnel into earth; and that the cliff evidently has a path across the face of it somewhere below the castle.

It may well have the complex, village-like sprawl of Edinburgh castle, with low, fortified walls zig-zagging around the projections but it must be draped over the top of an irregular rock rather than a sheer cliff - but one with earth piled against it on the side away from the water, smoothing the slope of the natural stone and the path above the lake running safely inside the walls: you can see in this picture of Edinburgh castle, for example, that there is a path crossing the slope between the first and second set of walls. Hard-walled underground features such as the dungeons and the Chamber of Secrets may be set into caves in the rock the castle stands on,

underneath the piled-up soil, or they may be actual buildings over which earth has been poured.

When little add-on turrets came into fashion in Scotland, the Hogwarts staff used magic as an aid to architecture and probably went a little mad sticking turrets all over the place.

I showed in the section on the location of Hogwarts that the castle is most probably either in the Kintail/Lochalsh region of the West Highlands, or in Galloway. It seems unlikely the Founders would have imported the stone for Hogwarts from far away for no obvious reason, so the school is probably made of similar stone to other castles in the area.

Castles in Galloway range from iron grey to the fairly definite pink of Caerlaverock, but seem for the most part to be quite brown. Castles are more thinly scattered in the West Highlands and some survive only as a few tumbled ruins, but the two major still-standing castles in the Lochalsh area, the reconstructed-Mediaeval Eilean Donan and the Victorian Duncraig, are both a warm brownish-grey: although Eilean Donan can look almost as red as Caerlaverock in some lights. So we can guess that Hogwarts, too, is quite a warm brown-grey, probably with a red cast in some lights: the colour of the stonework is evidently one thing Warner Brothers did get perfectly right.

There are two other, less obvious probable inspirations for the Hogwarts in the books. Wyedean Comprehensive, the secondary school JK Rowling and her sister went to, has typical 1960s architecture but it's a mile from Chepstow castle, a quarter of a mile from a sizeable copse, and one and two-thirds miles from the edge of the Forest of Dean. Many of the staff at Hogwarts are identifiably at least partially based on real staff at Hogwarts: Snape, for example, is about two-thirds John Nettleship, Rowling's Chemistry master, and the school boasted a teacher called Mr Mooney; another teacher who liked to weird the students out by removing his glass eye; an enormously tall French mistress; a hulking, hairy but emotionally sensitive biker Biology teacher etc.. Wyedean had a house-system which was a source of fierce competitiveness among staff as well as pupils, a school pond and - rather unexpectedly - its own pumpkin patch.

View of Ampleforth Abbey and College looking north across the school playing fields, from Stephen Wright OSB

The other is Ampleforth, the very high-powered boarding school, known as "the Catholic Eton", which was attended by one of Rowling's cousins (and by my dad, somewhat longer ago). Ampleforth is a grand, rambling Victorian pile with extensive grounds, multiple playing fields and its own lakes, set against woodland in a remote, beautiful area of the Yorkshire Dales. It has, most significantly and strikingly, its own private train, which conveys students from King's Cross to the school and back at the beginning and end of every term. Nowadays this goes no nearer to the school than York and is drawn by an ordinary modern engine, but up until 1964 the school had its own tiny local railway station and there was a time - certainly up to the 1950s, and perhaps more recently -

View of the south-east corner of Ampleforth Abbey and College, © Elliott Simpson at Geograph

when the Ampleforth train was powered by steam. My father rode the Hogwarts Express, for real.

Ampleforth encourages students to take part in character-building and faintly dangerous activities such as sailing, and has the reputation of being a place where students are encouraged to develop their characters, think independently and be able to argue their own viewpoint, and where the staff relate to the students as individuals and are willing to debate with rather than dictate to them. And it does, admittedly, look a little like the Warner Bros. idea of Hogwarts - even if not much like anything you would expect Harry to think of as a castle.

Basic layout

He then climbed out of the portrait hole, up through the silent castle [cut], finally arriving at the Owlery, which was situated at the top of West Tower. [GoF ch. #15; p. 201]

They left the Owlery together. At the entrance of a corridor that led towards the west wing of the castle, Cho said, 'I'm going this way. Well, I'll ... I'll see you around, Harry.' [OotP ch. #14; p. 256]

'Right, then. We're thinking of doing it tomorrow, just after lessons, because it should cause maximum impact if everybody's in the corridors – Harry, we'll set it off in the east wing somewhere, draw her right away from her own office' [OotP ch. #29; p. 580]

[cut] he set off at a run, weaving in and out of students now hurrying in the opposite direction to see what all the fuss was about in the east wing. [OotP ch. #29; p. 588]

Fred and George had made sure nobody was likely to forget them too soon. For one thing, they had not left instructions on how to remove the swamp that now filled the corridor on the fifth floor of the east wing. [OotP ch. #30; p. 596]

Harry and Hermione rushed up to the hospital wing at the end of the day to find Ron in a terrible state in bed. [PS ch. #14; p. 174]

Harry swallowed and looked around him. He realised he must be in the hospital wing. [PS ch. #17; p. 214]

He slumped back into bed, his eyes on the dark doorway to the hospital wing as the footsteps drew nearer. [CoS ch. #10; p. 134]

Justin was carried up to the hospital wing by Professor Flitwick and Professor Sinistra [CoS ch. #11; p. 152]

Hermione remained in the hospital wing for several weeks. [CoS ch. #13; p. 170]

'This will be a bit of a shock,' said Professor McGonagall in a surprisingly gentle voice as they approached the hospital wing. [CoS ch. #14; p. 190]

'We haven't seen her for ages, Professor,' Harry went on hurriedly, treading on Ron's foot, 'and we thought we'd sneak into the ¦hospital wing, you know, and tell her the Mandrakes are nearly ready and, er, not to worry.' [CoS ch. #16; p. 213/214]

Harry went back into the corridor with Madam Pomfrey, who left for the hospital wing, muttering to herself. [PoA ch. #05; p. 71]

For Harry knew who that screaming voice belonged to now. He had heard her words, heard them over and over again during the night hours in the hospital wing while he lay awake, [PoA ch. #10; p. 138]

They had reached the end of the corridor with the hospital wing entrance. 'OK – I can hear Dumbledore,' said Hermione tensely. 'Come on, Harry!' [PoA ch. #22; p. 305]

Sirius nodded, and stood up. He transformed back into the great black dog, and walked with Harry and Dumbledore out of [Dumbledore's] office, accompanying them down a flight of stairs to the hospital wing. [GoF ch. #36; p. 607]

Everything around him became hazy; the lamps around the hospital wing seemed to be winking at him in a friendly way through the screen around his bed; [GoF ch. #36; p. 608]

He had avoided being in the Great Hall when it was full ever since he had left the hospital wing, [GoF ch. #37; p. 624]

How long would it take Snape to release Montague from the toilet? Would he come straight back to his office afterwards, or accompany Montague to the hospital wing? [OotP ch. #28; p. 563]

[cut] Harry ran up the marble staircase, hurtled along the corridors so fast the portraits he passed muttered reproaches, up more flights of stairs, and finally burst like a hurricane through the double doors of the hospital wing, [OotP ch. #32; p. 643]

Professor Umbridge left Hogwarts the day before the end of term. It seemed she had crept out of the hospital wing during dinnertime, [OotP ch. #38; p. 755]

Where was Malfoy? He did not seem to be at the Slytherin table in the Great Hall, eating breakfast ... he was nowhere near Snape, who was sitting in his study ... he wasn't in any of the bathrooms or in the hospital wing ... [HBP ch. #18; p. 366]

Harry blinked and looked around. Of course: he was in the hospital wing. [HBP ch. #19; p. 389]

They had reached the hospital wing: pushing open the doors, Harry saw Neville lying, apparently asleep, in a bed near the door. [HBP ch. #29; p. 571]

We know that Hogwarts has a west wing, an east wing and a hospital wing. A wing is normally a long spur sticking off from the main building, joined to it only at one end and usually perpendicular to it - like the horizontal bars on a letter E or a square bracket.

The shape isn't always that elegant - Borthwick (a) is shaped like a nearly-square block with a notch in it and the "wings", so called, are just the chunky oblong blocks either side of the notch - but there is an implication of discrete sections at right-angles to the long axis of the building, or to the frontage where the main entrance is.

However, Hogwarts cannot consist simply of a main building with cross-bars. We know this because the main door seems to be on the front face of the main building, according to JK Rowling's own map, and the evening sun shines in through the main doors on a date when the sun is around 32° north of due west (see the section on the grounds of Hogwarts).

In order for the main, front face of the castle to have an east and west end - and therefore an east and west wing in a simple square-bracket shape - that front face would have to face north or south (b). If the front face of the castle faced broadly north, there could be a fairly short wing at the west end at right-angles to the main facade, without it preventing the June sunset from shining in the doors. [Note the accompanying diagrams are simplified into blocks, but the actual shape of Hogwarts will be much more complex, with courtyards etc.. These are just simple schematics to show how I did the working-out.]

However we know, from the information we have about the grounds of Hogwarts, that the Forbidden Forest is west and north-west of the castle and that the Forest is on the right as you walk from the castle to the gates. This means that the gates are more or less south of the castle. We also know that the front of the castle faces more or less towards the Forest - and therefore towards the west - and that there is a line-of-sight from the main doors to the gates. So the castle faces more or less south and/or west.

We also know, however, that the setting sun shines in through the main doors (although it must do so at quite an angle) at a point when the sunset would be about 32° north of west, so the doors cannot be strongly angled to the south: if they were, the sun wouldn't be able to shine in through the door at this angle. But nor can they face north of west, because then they wouldn't command a view of the gates, which are to the south. They must face as close to true west as they can and still command a view of the gates.

This makes the existence of a west wing much more problematic. The front of the castle has a west face, not a west end, or at the least a south-west face: so the nearest it could get to having a "west" wing at right-angles to the front would be to have a north-west wing. And any wing sticking out from the north-west side of the doors would have to be pretty short, otherwise it would cut out the sunset light.

So, there cannot be a west wing in the usual sense - a right-angled cross-bar at the west end of a building whose main axis runs east to west. We also know there isn't a wing jutting out more than a few yards from the main face of the building to the right of the main doors as you face them, because (as established in the section on the grounds of Hogwarts) the lake is broadly south-east of the castle and you can stand on the lawn at the front of the castle, look to the side and see the centre of the lake, and a projecting wing in this position would obscure the view.

Even if you imagine the building as a distorted E with the middle leg

longer and wider than the end ones (c), so that the side-wings don't interrupt the lines of sight from the main doors, you still have the problem that the front of the building has to be aligned so that the sunlight shines into the Entrance Hall when the sun is at 32° north of east, so the front face of the building cannot really be any closer to an east-west alignment than south-east to north-west, and the side wings ought to be the south-east and north-west wings. Instead of which, we have a separate West Tower and North Tower.

You can get round this to some extent by imagining

that the front of the castle slopes relative to the main axis, so that the front and main doors face south-west while the main axis runs east-west (d): castles tend to be built to follow the lie of the land underneath them, so this sort of irregular shape is perfectly possible. But then you have to consider the description of the position of the West Tower and Filius Flitwick's office.

Flitwick's office is on the seventh floor, thirteen windows to the right of the West Tower. The Owlery is in the West Tower, and when you leave the Owlery you pass a turning leading to the West Wing - so the West Tower is not actually on the West Wing, although it may be at one end of it, with a turning to the West Wing and a turning to the main block.

Coming up from the bushes by the lakeside on Buckbeak, from a starting position from which they were able to see the main doors, Harry and Hermione fly towards the castle and then bear left to get to Flitwick's office. This suggests four possibilities. Either Buckbeak flies straight at the front of the castle and then turns left along the main face of it; or he flies at the side of the castle and turns left along it; or he flies towards the main face of the castle at a shallow angle and then turns left along a block at right angles to the main face; or he bears left and around in a U-shape, following a block which sticks out from the castle and reflexes back parallel to it. In the last two cases the block must be big enough to have at least fifteen windows on the top floor to the right of the tower, probably a lot more, because if Flitwick's office were right in the corner between this block and the front face of the castle, you'd expect Dumbledore to say e.g. "second window left of the corner".

'Now, pay attention,' said Dumbledore, speaking very low, and very clearly. 'Sirius is locked in Professor Flitwick's office on the seventh floor. Thirteenth window from the right of the West Tower.' [PoA ch. #21; p. 288]

       Together they peered around the bush at the other bank.[cut]
       They waited, watching the moving clouds reflected in the lake, while the bush next to them whispered in the breeze. Buckbeak, bored, was ferreting for worms again. [cut]
       'Look!' Hermione whispered. 'Who's that? Someone's coming back out of the castle!' [PoA ch. #21; p. 301/302]

       Harry urged Buckbeak forwards. They were gliding quietly towards the upper floors of the castle ... Harry pulled hard on the left-hand side of the rope, and Buckbeak turned. Harry was trying to count the windows flashing past – [cut]
       Black placed a hand on either side of the window-frame and heaved his head and shoulders out of it. It was very lucky he was so thin. In seconds, he had managed to fling one leg over Buckbeak's back and pull himself onto the Hippogriff behind Hermione.
       'OK, Buckbeak, up!' said Harry, shaking the rope. 'Up to the tower – come on!'
       The Hippogriff gave one sweep of its mighty wings and they were soaring upwards again, high as the top of the West Tower. Buckbeak landed with a clatter on the battlements and Harry and Hermione slid off him at once. [PoA ch. #21; p. 302/303]

He then climbed out of the portrait hole, up through the silent castle [cut], finally arriving at the Owlery, which was situated at the top of West Tower. [GoF ch. #15; p. 201]

We know that we want there to be a block sticking out from the castle, with the West Tower on it, because the only way there can really be a West Tower or west wing is if it sticks out to the west (the front or Forbidden Forest side) of the castle. And it must be towards the left of the point at which Buckbeak approached the main block, because Harry turns left in order to look for a window which is right of the West Tower.

We know the lake is at the back and south side of the castle (see section on the grounds), not in front of it - the Forest is in front of it. In some ways it would make a lot of sense to think that Buckbeak flew at the side wall of the main block of the castle and then turned left (e), placing the West Tower and the West Wing (which we know is near it) at the near corner of the building. But we already know the main block faces south-west or west-south-west, which means the end nearest the lake - the end Buckbeak would approach from - is the south-east end, and further east than the other end. In order for the West Tower genuinely to be west of the main block - or even of half of it - it would have to stick out a long way to the west, and yet we also know (see section on the grounds again) that Harry, standing just in front of the main doors, can see past the side of the castle to the centre of the lake, to his left if he has his back to the castle, and that from the main doors you can see south or south-west to the main gates

The only way to make it work would be to assume that the stretch of castle in which Flitwick's office is located, projecting from the south-west corner of the castle, is pierced with open arcades so that one can see through it to the lake and the gates, and so that Harry and Hermione can see from the lakeside right through it to the main doors. This is just about possible, although such arcades usually edge graceful courtyards, and this one would instead be striding down the side of the steep slope in front of the castle. It's an attractive idea - but it would probably interfere with the line of sight between the main doors and the front gates, breaking up the view across a row of arches, and we're not given any reason to think that this is so.

On the other hand, in order for Buckbeak to fly more or less straight at the main face of the castle before turning hard left along the main face of the building, and coming as he is from a point at the side, he would have to have come round in a wide curve (f).

That makes it more likely Flitwick's office is on a block that sticks out, and Buckbeak flew at the castle at a shallow angle and then turned left along this separate block (g) - especially as we know we need there to be such a west-projecting block.

Yet, this block cannot itself be the west wing, because we're back to the fact that if the front of the castle is angled to catch the setting sun, any wing perpendicular to it would be at least as much northern as western. Even more strikingly, Harry and Cho would have had to walk through this block to get from the Owlery back to the main body of the castle, yet the west wing is clearly a side-turning which Harry bypasses.

Therefore, this putative nor'-westerly block where Flitwick's office is, more or less at right-angles to the front of the building, cannot be the west wing - nor can it stick out very far to the west, or it would prevent the setting sun from shining through the main doors. Yet it clearly is to the west of the castle, since it includes the West Tower. The west wing must be a spur running off from this block - but if it projected from Flitwick's block back across the front of the castle (h), that would put the fifteen-plus-windows-wide face where Flitwick's office is, and the West Tower, on the inside of an angle, making the whole western section as wide as those fifteen windows plus the West Tower plus the width of the west wing, and it would probably stick out too much and obscure the light from the sunset.

It would also probably require the West Tower to be wide enough to protrude on both the inner and outer sides of the west wing, since a tower which stuck out only on the inside of an angle would not improve coverage of the area around it, and would therefore serve no defensive purpose.

Since the west wing is substantial enough to qualify as a wing, and yet it doesn't prevent the light from a west-nor'-west sunset from shining in through the main doors, it probably points away from the main body of the castle, not back across it (i). The east wing may run in the same direction (j) - although it would need to stick out a long way, as it would be springing from the westmost end of the main block - or it might be at the other end (k), so long as it doesn't stick out so far as to obscure the view of the lake. Since we don't need to worry about the east wing interrupting the light, it could reflex back parallel to the building or at an angle (l)

This gives us a sensible east-west axis to the main building, with wings coming off it at right-angles to the east and west ends: it's just that it's on the side(s) of the castle, not the front face where the main doors are.

We still have to think about how far the western block sticks out from the front of the castle. If Flitwick's window is in this block then we have say eighteen windows (there have to be significantly more than fifteen) plus the width of the tower.

The window is very narrow - Sirius can barely squeeze through - and the rooms may also be narrow, although you have to allow for the thickness of the walls between the rooms. Say the windows are at 8ft intervals, that's 144ft, plus say 45ft for the tower (the towers at Chepstow range from about 30-45ft in diameter) is 189ft, or around 63 yards. If we assume Hogwarts over all is about the same size as Edinburgh Castle - about 350 yards long - and we twiddle it about a bit as far as it will go, so the castle faces west-sou'-west (m), the gates are slightly west of south and the main doors are displaced to the right instead of central, we can fit in a projecting block of that size (or a little bigger if we want to accommodate more windows) and still have the sun shining in through the main doors - albeit at a nearly 40° angle - and the doors still commanding a view of the gates.

Roatating the castle in this way so its long axis runs nor'nor'west to sou'sou'east, rather than north-west to south-east, also enables us to have an east wing which doesn't need to stick out hugely far from the main building in order to be east of it.

There's another good reason to think that Flitwick's office is in a block at right angles to the front of the building. Dumbledore tells Harry that Flitwick's office is fifteen windows to the right of the West Tower - only that. Without receiving further instructions Harry then flies at the front of the building, bears left and counts windows as he heads left, in order to arrive at a window which is fifteen places right of the tower - that is, he's counting from the other direction. Either Harry - or Hermione - knows the castle so completely that he can say e.g. "If it's fifteen windows right of the West Tower it must be twenty-seven windows left of the main doors", or while he's been waiting by the lake he's been counting windows so he knows the count in both directions. And since the place where he was waiting was towards the side of the castle rather than the front, it would be difficult for him to see well enough to count the windows on the front face of the castle: they would be very much foreshortened. The windows he is looking at and counting must either be on the side of the castle nearest him, or on a wing sticking out from the castle, and the second option causes fewer problems.

Harry left the changing room alone some time later, to take his Nimbus Two Thousand back to the broomshed. [cut]
       Harry had reached the shed. He leant against the wooden door and looked up at Hogwarts, with its windows glowing red in the setting sun. [cut]
       A hooded figure came swiftly down the front steps of the castle. Clearly not wanting to be seen, it walked as fast as possible towards the Forbidden Forest.[cut]
       Harry jumped back on his Nimbus Two Thousand and took off. Gliding silently over the castle he saw Snape enter the Forest at a run. He followed. [PS ch. #13; p. 165]

We also need to consider the fact that in PS Harry stands by the broomshed, and he can see the main doors and the face of the castle which faces the sunset (he can see the sunset reflected in the windows), yet part of the castle is evidently between him and part of the Forest - which ought to be in much the same direction as the sunset, since the Forest is to the west. He has to fly up over the castle in order to see Snape entering the Forest in order to meet Quirrell. This suggests that the broomshed is tucked in in some way. Since we already know that the north-west block probably sticks out towards the Forest, the logical place for the shed to be is tucked in against it.

It could be that it's on the south side of the block, towards the main doors, but tucked into the angle at the base of the West Tower which obscures the view of the Forest.

Even better, it could be on the north side of the block, probably in a courtyard, but the ground floor of the block be pierced by an archway which enables someone standing by the shed to see the main doors (n). That would definitely explain why Harry flew up over the castle to see Snape enter the Forest, since otherwise he would have had to fly back the other way through a low arch, and then round the base of the West Tower.

We must assume, though, that if there is indeed a passage through the block where Flitwick's office is, connecting the open-air space in front of the castle with an open-air space where the broomshed is, that passage is either small, or it can be heavily barred, or it goes nowhere strategically useful: because there's no mention of the giants or Death Eaters trying to storm it during the Battle of Hogwarts.

We cannot get around the problem of the setting sunlight needing to reach the main doors by assuming a projecting west wing which is to the left of the main doors and is pierced by arcades at gound level, incidentally, unless it's stone lacework for a couple of floors above as well. As shown in the essay on the setting of Hogwarts, there are mountains to the west which cause the sun to set earlier and higher in the sky than it would do in flat countryside, so the light of the setting sun wouldn't be coming in horizontally but down from a height. He let them all leave in threes and fours, watching their tiny dots anxiously to see that they returned safely to their dormitories: [cut] Ravenclaws to a tower on the west side of the castle [OotP ch. #18; p. 351]

Note that Ravenclaw Tower is on the west side of the castle. When Harry and Cho leave the Owlery (which is at the top of the West Tower) Ravenclaw Cho heads for the west wing, so Ravenclaw Tower may well be on that wing, probably at the far end.

'They look like they might be breaching the North Battlements, they've brought giants of their own!' [DH ch. #31; p. 503]

During the Battle of Hogwarts enemy giants attack the North Battlements. These could be the north-facing side-wall of the main castle, in between the east and west wings, or they could be a battlemented curtain wall joining the east and west wings. Calling them the North Battlements, with capital letters, makes it sound as if they are a feature which is just battlements, not just battlements as a fringe on top of something else, so it seems likely that a curtain wall is meant: just a vehicle for having battlements on. There would then be a section of courtyard bounded by the east and west wings, the North Battlements and the north side of the main castle, and containing (probably among many other things) the broomshed.

He could see mountains and forests under a deep-purple sky. The train did seem to be slowing down. [PS ch. #06; p. 82/83]

Then they clambered up a passageway in the rock after Hagrid's lamp, coming out at last onto smooth, damp grass right in the shadow of the castle.
They walked up a flight of stone steps and crowded around the huge, oak front door. [PS ch. #06; p. 84]

If the tunnel which leads up from the boat-landing under the cliff can be sealed and defended at the lake end, and especially if it interconnects with the dungeons or cellars, then it would make sense for it too to emerge inside this putative courtyard which overlooks the lawn in front of the main doors, but which evidently can be barred. That way if the castle were under seige the defenders could go down to the water without leaving the secure perimeter of the castle.

On the face of it the description sounds more as if the tunnel simply emerges onto the lawn in front of the castle, but we are told that the tunnel mouth is actually in the shadow of the castle. Since the castle faces west, and in early September the sun sets almost due west, if a shadow cast by the sun is meant then the tunnel mouth cannot simply be out on the lawn in front of the castle: it must be tucked in amongst walls or buildings more westerly than it is. The same applies if the shadow is one cast by the lights of the windows: you'd expect the lawn in front of the main doors to be lit up, not shadowed. Either of these cases would be evidence that the tunnel mouth opened into the courtyard where the broomshed is, and from which we know the main doors can be seen. If so, we can say that that area of courtyard is grassed.

However, it's not clear whether there is still any sun to cast shadow, since the sky was already deep purple when they arrived at the train station and that must have been at least twenty minutes beforehand. If the shadow is the shadow cast by the moon, we do not know what time the moon rose that day/night in the Potterverse, and so the moonlight could well have cast the lawn in front of the main doors into shadow.

The hospital wing as described generally sounds like a long ward with an office off it. However, the fact that it is called the hospital “wing” implies that an entire spur of building is dedicated to it: and one with several floors at least, since it usually seems to be entered quite high up. Perhaps the other floors are used for research; for quarantine facilities to contain infectious diseases; for Madame Pomfrey's private quarters; for the treatment of house-elves and perhaps even veterinary facilities for e.g. injured unicorns. If the wing itself is a small one, really just something the size of a smallish house sticking off from the main body of the castle, there could easily be two or even three floors devoted to Madame Pomfrey's quarters.

Of course, if Red Hen is right and St Mungo's Hospital was originally based at Hogwarts, the extra capacity in the hospital wing may now be surplus to requirements and standing empty. 'Shocking business ... shocking ... miracle none of them died ... never heard the like ... by thunder, it was lucky you were there, Snape ...'
       'Thank you, Minister.'
       'Order of Merlin, Second Class, I'd say. First Class, if I can wangle it!' [cut]
       [cut] Fudge consulted the large gold pocket watch dangling from his waistcoat.
       'The Dementors should have arrived by now,' he said. 'I'll go and meet them. Dumbledore, I'll see you upstairs.' [cut]
       'Now, pay attention,' said Dumbledore, speaking very low, and very clearly. 'Sirius is locked in Professor Flitwick's office on the seventh floor. Thirteenth window from the right of the West Tower. [cut]
       'I am going to lock you in. It is –' he consulted his watch, 'five minutes to midnight. Miss Granger, three turns should do it. Good luck.' [PoA ch. #21; p. 283-288]

       Hermione was tugging at his sleeve, staring at her watch. 'We've got exactly ten minutes to get back down to the hospital wing without anybody seeing us – before Dumbledore locks the door –'
       'OK,' said Harry, wrenching his gaze from the sky, 'let's go ...'
       They slipped through the doorway behind them and down a tightly spiralling stone staircase. As they reached the bottom of it, they heard voices. They flattened themselves against the wall and listened. It sounded like Fudge and Snape. They were walking quickly along the corridor at the foot of the staircase.
       ' ... only hope Dumbledore's not going to make difficulties,' Snape was saying. 'The Kiss will be performed immediately?'
       'As soon as Macnair returns with the Dementors. This whole Black affair has been highly embarrassing. I can't tell you how much I'm looking forward to informing the Daily Prophet that we've got him at last ... I daresay they'll want to interview you, Snape ... and once young Harry's back in his right mind, I expect he'll want to tell the Prophet exactly how you saved him ...'
       Harry clenched his teeth. He caught a glimpse of Snape's smirk as he and Fudge passed Harry and Hermione's hiding place. Their footsteps died away. Harry and Hermione waited a few moments to make sure they'd really gone, then started to run in the opposite direction. [PoA ch. #22; p. 304]

       'I am going to lock you in,' they heard him saying. 'It is five minutes to midnight. Miss Granger, three turns should do it. Good luck.'
       Dumbledore backed out of the room, closed the door, and took out his wand to magically lock it. Panicking, Harry and Hermione ran forwards. Dumbledore looked up, and a wide smile appeared under the long silver moustache. 'Well?' he said quietly.
       'We did it!' said Harry breathlessly. 'Sirius has gone, on Buckbeak ...' [cut]
       Harry and Hermione slipped back inside the dormitory. [cut] A moment later, Madam Pomfrey came striding back out of her office.
       'Did I hear the Headmaster leaving? Am I allowed to look after my patients now?'
       She was in a very bad mood. Harry and Hermione thought it best to accept their chocolate quietly. Madam Pomfrey stood over them, making sure they ate it. [cut] And then, as they both took a fourth piece of chocolate from Madam Pomfrey, they heard a distant roar of fury echoing from somewhere above them ...[cut]
       Now they could hear angry voices, growing louder and louder. Madam Pomfrey was staring at the door. [cut]
       Fudge, Snape and Dumbledore came striding into the ward. Dumbledore alone looked calm. Indeed, he looked as though he was quite enjoying himself. Fudge appeared angry. But Snape was beside himself. [cut]
       'YOU DON'T KNOW POTTER!' shrieked Snape. 'HE DID IT, I KNOW HE DID IT –'
       'That will do, Severus,' said Dumbledore quietly. 'Think about what you are saying. This door has been locked since I left the ward ten minutes ago.' [PoA ch. #22; p. 305/306]

We know that the hospital wing is a few minutes' walk from the West Tower. In PoA, when Harry and Hermione use the Time-Turner to rescue Sirius and Buckbeak, they leave the hospital wing at five to midnight and have to get back at the same time. A few minutes beforehand, Snape and Fudge are in the hospital wing talking and they then set out intending to see Sirius executed, saying that the Dementors must have arrived by now. From the point at which Harry wakes and hears Snape and Fudge talking to the point at which Dumbledore says it is five minutes to midnight, a minute or two after they have left, takes at least four and a half minutes (I timed how long it took to say everything that was said), and that's assuming that Snape and Fudge had only arrived the moment Harry woke and were talking very fast and without pause, neither of which we know. Allowing a little leeway, then, we can say Snape and Fudge are probably in the hospital wing between, say, eleven and seven minutes to the hour.

Time-Turned Harry and Hermione rescue Sirius and Buckbeak, then descend the West Tower to the seventh floor. At this point it is just under ten minutes before they have to be back in the hospital wing, so it is about fourteen minutes to midnight. Close to the exit from the tower, Fudge and Snape pass them by, talking about the fact that the Dementors have been sent for - so clearly this is before the scene in the hospital wing, as far as Snape and Fudge are concerned. So they get from the West Tower to the hospital wing in three or four minutes, while Harry and Hermione take nine minutes to cover an alternative, longer route in order to avoid them, arriving back at the hospital wing at five to midnight, after Snape and Fudge have been and gone.

When Harry and Hermione see Snape and Fudge near the West Tower they have probably come from checking on Sirius, so the West Tower is in between Flitwick's office (where Sirius was held) and the hospital wing, at least as far as easily-walked routes go.

So, Snape and Fudge are at the West Tower at fourteen minutes to midnight and in the hospital wing from around eleven to seven minutes to the hour. They then leave the hospital wing and return to where Sirius had been being held, in the West Wing, where they find that Sirius has gone. They then storm back to the hospital wing. After maybe thirty seconds of conversation Dumbledore says that it is ten minuts since he locked the ward door at five to midnight, so we know they got back to the hospital wing just after 12:04am, having left it at about 11:53pm. So it has taken them around eleven minutes to get to Flitwick's office - which we know is beyond the West Tower, relative to the hospital wing - discover that Sirius was gone, search the area, discuss the matter with Macnair, tell the Dementor its services are not required and then return.

So, it takes about three minutes to get from the West Tower to the hospital wing. Assuming Snape and Fudge were walking fairly briskly, and allowing for the fact that they had to come down at least one stair, that's around two hundred yards. Flitwick's office is slightly further on and they spent probably four minutes faffing around with Macnair and the Dementor.

They finished lunch and went outside into the overcast courtyard. Hermione sat down on a stone step [CoS ch. #06; p. 75]

Loud and scathing, Draco Malfoy's voice echoed around the courtyard. [CoS ch. #06; p. 75]

'Oh, don't give me that rubbish,' said Hermione, but she looked slightly mollified as she led the way out into the damp courtyard.
A fine misty drizzle was falling, so that the people standing in huddles around the edges of the yard looked blurred at the edges. Harry, Ron and Hermione chose a secluded corner under a heavily dripping balcony, [cut] when someone walked around the corner towards them. [OotP ch. #12; p. 207]

She walked away. Hermione waited until Cho was halfway across the courtyard before rounding on Ron. [OotP ch. #12; p. 208]

Professor McGonagall gave him a curt nod and retreated into the staff room, leaving Harry to be swept out into the courtyard with the crowd. He spotted Ron and Hermione already standing in a sheltered corner, [OotP ch. #17; p. 319/320]

'Maybe I'll skive off Divination,' he said glumly, as they stood in the courtyard after lunch, [OotP ch. #17; p. 324]

Standing in their usual corner of the cool and breezy courtyard, Harry told her every detail of the dream he could remember. [OotP ch. #26; p. 518]

They were sitting with Ron in a sunny corner of the courtyard after lunch. [HBP ch. #22; p. 439]

Lily and Snape were walking across the castle courtyard [cut]
Lily had reached a pillar and leaned against it, [DH ch. #33; p. 540]

Other than that, there are no immediately obvious clues as to where in the castle the hospital wing is, or even whether it is a wing which projects outwards from the castle, or inwards into the courtyard: that will require more detailed analysis. It's certainly the case both that the courtyard at Hogwarts is a complex shape, with secluded areas and corners you can walk round and appear round the edge of, and that you would expect a substantial Mediaeval castle to have discrete buildings and blocks within the outer perimeter, as we see for example at Caldicot castle where there are domestic, house-like buildings and even gardens within a more stark curtain wall. The hospital wing at Hogwarts can definitely be accessed without going outside but it could potentially be linked to the main body of the castle only by e.g. a curtain wall with a passage inside it.

Some of the staff may well live in free-standing houses within the courtyards. Indeed, it would explain the anomaly that you would expect a large, complex castle to have several courtyards, and yet the students seem to have access to only one, since we only ever hear of them going into "the" courtyard, never "a" courtyard or "the main" courtyard. The others may contain private staff quarters, and be off-limits to students.

Snape hurtled through a classroom door [cut]
       [cut] Harry dragged [Luna] into the deserted classroom where Professors McGonagall, Flitwick and Sprout were standing at a smashed window. [cut]
       [cut] Harry sprinted to the window [cut]
       With a tingle of horror, Harry saw in the distance a huge, bat-like shape flying through the darkness towards the perimeter wall. [DH ch. #30; p. 482]

Yet, Hogwarts must be of a chunkier and more complex construction than the typical English/Welsh Mediaeval castle. There are too many rooms for it to be a thin skin of narrow walls and a few buildings around a wide open space for mustering soldiers, and we know that there are classrooms right in the outer face of the the castle because Snape flies from a classroom out over the grounds, not over the courtyard: it is pretty clear from the time it takes Harry to get to the window after Snape has jumped, and the fact that he sees him as being in the distance and yet not having reached the wall yet, that Harry is seeing Snape flying over the grounds towards the boundary-wall,

not across the courtyard to a curtain wall. So Hogwarts must be some sort of hybrid between the castle-as-walls-around-open-space of England and Wales and the castle-as-socking-great-solid-block of Scotland.

It could be like the thirteenth century castle of Mont Orgueil (a.k.a. Gorey castle) on Jersey in the Channel Isles, which has a massive main keep part of which forms part of the outer perimeter, set in a lacework of criss-crossing walls and courtyards and smaller buildings, draped over uneven ground. But at Hogwarts the walls are definitely wide enough to have under-cover passages through them. This is by no means unlikely - glossaries of castle nomenclature mention the possibility of "wall-walks" being roofed in some cases - and it would explain why there are so many and so complex corridors at Hogwarts, some of which seem to have windows looking out on both sides. Indeed you might expect that a castle which was exposed to the vagaries of the Highland weather would be more roofed-over than one in the Channel Isles.

On the face of it, it doesn't make much sense to have a castle which on the one hand encloses protected space - it has a courtyard, and battlements - and on the other has the main door of the main keep opening from the interior of the building to the outside of the castle, although the proximity of the Astronomy Tower would provide some fire-power to cover the door. You would expect to have to come through a defended gateway and into a courtyard before you got to the door of the keep; or, if the model is a Scottish fortified tower house, you would expect the door to be a bit harder to get at, and not to open straight It was when he reached the bottom step that it occurred to him how very pleasant it would be to pass the vegetable patch on his walk to Hagrid's. It was not strictly on the way, but it seemed clear to Harry that this was a whim on which he should act, so he directed his feet immediately towards the vegetable patch where he was pleased, but not altogether surprised, to find Professor Slughorn in conversation with Professor Sprout. Harry lurked behind a low stone wall, feeling at peace with the world and listening to their conversation. [HBP ch. #22; p. 448] into the interior without any sort of small lobby where invaders could be trapped. Some fortified houses had front doors which had to be climbed up to on removable ladders, and many originally had a small curtain wall enclosing a yard at the front and protecting the door, or had no windows at ground level - see for example these articles on Scottish tower houses, pele towers and house-keeps. Hogwarts seems unusually exposed.

However, there is a mention of an unexplained wall at the edge of the vegetable patch. It's described as low, but it's possible it's the last ruined remnant of a length of curtain wall which originally enclosed a defensible space in front of the main doors: it would certainly make sense for the vegetable patch to have originally been within the defensive wall, to feed the castle in the event of a siege. In that case, of course, the tunnel from the lake may very well open onto the lawn in front of the castle, because that would originally have been inside the outer wall.

       The Hall was starting to empty as people headed off towards their first lesson. Ron checked his timetable.
       'We'd better go, look, Divination's at the top of North Tower. It'll take us ten minutes to get there ...' [cut]
       The journey through the castle to North Tower was a long one. Two years at Hogwarts hadn't taught them everything about the castle, and they had never been inside North Tower before.
       There's – got – to – be – a – short – cut,' Ron panted, as they climbed their seventh long staircase and emerged on an unfamiliar landing, where there was nothing but a large painting of a bare stretch of grass hanging on the stone wall.
       'I think it's this way,' said Hermione, peering down the empty passage to the right.
       'Can't be,' said Ron. That's south. Look, you can see a bit of the lake out of the window ...' [PoA ch. #06; p. 77]

       'Listen,' said Harry, taking advantage of the knight's exhaustion, 'we're looking for the North Tower. You don't know the way, do you?' [cut]
       'Be of stout heart, the worst is yet to come!' yelled the knight, and they saw him reappear in front of an alarmed group of women in crinolines, whose picture hung on the wall of a narrow spiral staircase.
       Puffing loudly, Harry, Ron and Hermione climbed the tightly spiralling steps, getting dizzier and dizzier, until at last they heard the murmur of voices above them, and knew they had reached the classroom. [cut]
       They climbed the last few steps and emerged onto a tiny landing, where most of the class was already assembled. There were no doors off this landing; but Ron nudged Harry and pointed at the ceiling, where there was a circular trap door with a brass plaque on it.
       'Sibyll Trelawney, Divination teacher', Harry read. 'How're we supposed to get up there?'
       As though in answer to his question, the trapdoor suddenly opened, and a silvery ladder descended right at Harry's feet. Everyone went quiet. [PoA ch. #06; p. 78]

Harry's and Ron's last exam was Divination; Hermione's, Muggle Studies. They walked up the marble staircase together. Hermione left them on the first floor and Harry and Ron proceeded all the way up to the seventh, where many of their class were sitting on the spiral staircase to Professor Trelawney's classroom, trying to cram in a bit of last-minute revision. [PoA ch. #16; p. 236]

Harry climbed back down the ladder and the spiral staircase, wondering ... had he just heard Professor Trelawney make a real prediction? Or had that been her idea of an impressive end to the test?
Five minutes later he was dashing past the security trolls outside the entrance to Gryffindor Tower, [PoA ch. #16; p. 238/239]

When the bell rang to signal the start of afternoon lessons, Harry and Ron set off for North Tower where, at the top of a tightly spiralling staircase, a silver stepladder led to a circular trapdoor in the ceiling, and the room where Professor Trelawney lived. [GoF ch. #13; p. 176]

'You were at the top of North Tower!' Hermione said. 'Your voice couldn't have carried all the way down to the grounds!' [GoF ch. #31; p. 532/533]

[cut] take groups of fighters up to the three highest Towers – Ravenclaw, Astronomy and Gryffindor – where they’ll have a good overview, excellent positions from which to work spells. [DH ch. #31; p. 491]

The North Tower must be at or near the northernmost corner of the castle - that's not a problem. If the front of the castle faces west-south-west and it is even vaguely oblong, then it will have identifiable northern and southern ends. Whenever anyone access the North Tower they do so from the seventh floor, and all we're told about is a very long spiral stair leading to a room which is sitting on the top of the tower. Yet, long though the stair is and tall though the tower must be, it is not one of the three tallest towers of Hogwarts.

It is ten minutes' walk and climb from the Great Hall, and about a five minute dash down the stairs and along the corridors to the Gryffindor Common Room. On the face of it these times imply that it is nearly half a mile from the Great Hall and more than half a mile from Gryffindor Tower, which is ridiculous: even Windsor Castle, the largest castle in Britain, is under six hundred yards long. We must assume that Harry didn't "dash" the whole way to Gryffindor Tower, and that the corridors in between weave about a lot. Even so, it tells us that Hogwarts is a very big castle. That doesn't necessarily mean it's huge in terms of living accommodation - it may have a lot of empty space enclosed by curtain walls - but it must extend over several hundred yards. 'Nearly there!' Harry panted as they reached the corridor beneath the tallest tower. [PS ch. #14; p. 175]

The steep spiral staircase up to the top of the tower seemed the easiest thing in the world after that. [PS ch. #14; p. 176]

[cut] being up the tallest astronomy tower, which was out-of-bounds except for classes [PS ch. #15; p. 177]

Then came Astronomy at midnight, up on the tallest tower; History of Magic on Wednesday morning, [PoA ch. #16; p. 234]

As Harry completed the constellation Orion on his chart, however, the front doors of the castle opened directly below the parapet where he was standing, so that light spilled down the stone steps a little way across the lawn. Harry glanced down as he made a slight adjustment to the position of his telescope and saw five or six elongated shadows moving over the brightly lit grass before the doors swung shut and the lawn became a sea of darkness once more. [OotP ch. #31; p. 633/634]

'Look!' squealed Parvati, who was leaning over the parapet and pointing to the foot of the castle where the front doors had opened again; more light was spilling out on to the dark lawn and a single long black shadow was now rippling across the lawn. [OotP ch. #31; p. 636]

The Dark Mark was glittering directly above the Astronomy Tower, the highest of the castle. Did that mean the death had occurred there?
Dumbledore had already crossed the crenellated ramparts and was dismounting; Harry landed next to him seconds later and looked around.
The ramparts were deserted. The door to the spiral staircase that led back into the castle was closed. [HBP ch. #27; p. 544/545]

Harry hurried over to the door leading to the spiral staircase, but his hand had only just closed upon the iron ring of the door when he heard running footsteps on the other side. [HBP ch. #27; p. 545]

'Yeah, well, you still didn't realise who was behind that stuff did you?' sneered Malfoy, as Dumbledore slid a little down the ramparts, the strength in his legs apparently fading, [HBP ch. #27; p. 549]

'Isn't that the secret method of communication the group that called themselves Dumbledore's Army used last year?' asked Dumbledore. His voice was light and conversational, but Harry saw him slip an inch lower down the wall as he said it. [HBP ch. #27; p. 550]

'Draco, do it, or stand aside so one of us –' screeched the woman, but at that precise moment the door to the ramparts burst open once more and there stood Snape, his wand clutched in his hand as his black eyes swept the scene, from Dumbledore slumped against the wall, [HBP ch. #27; p. 556]

He leapt the last ten steps of the spiral staircase and stopped where he landed, his wand raised: the dimly lit corridor was full of dust; [HBP ch. #28; p. 557/558]

Harry scrambled up from the floor and began to sprint along the corridor, [cut]
He skidded round the corner, his trainers slippery with blood; Snape had an immense head-start – was it possible that he had already entered the Cabinet in the Room of Requirement, [HBP ch. #28; p. 559]

'What're they all lookin' at?' said Hagrid, as he and Harry approached the castle front, Fang keeping as close as he could to their ankles. 'Wha's tha', lyin' on the grass?' Hagrid added sharply, heading now towards the foot of the Astronomy Tower, where a small crowd was congregating. 'See it, Harry? Righ' at the foot o' the Tower? Under where the Mark ... blimey ... yeh don' think someone got thrown –?' [HBP ch. #29; p. 567]

[cut] for an instant he knelt again beside Dumbledore’s body at the foot of the tallest tower at Hogwarts [DH ch. #24; p. 386]

The Astronomy Tower we know is next to the front doors (and it is a proper tower, not a turret, because it has a base which goes down to the ground). The statement that the front doors are "directly below the parapet" suggest that it is the sort of tower whose top is wider than its shaft. Note that Rowling is confused in her terminology: she clearly means "battlements" throughout, not "ramparts", which are steep earth slopes at the foot of a castle.

Gryffindor Tower is to the right of the front doors as you face them, which is to say, more-or-less at the southern end of the castle. We know this because JKR's own map shows the beech tree by the lakeside, where the Marauders bullied Severus, as being to the right of the doors and we know that one of the windows in Harry's dorm in Gryffinder Tower directly overlooks that tree and also commands a view of Hagrid's cabin. One of the windows shows the Whomping Willow and part of the Forest. As quietly as he could, he got out of his four-poster and went to pour himself some water from the silver jug beneath the window.
       The grounds were still and quiet. No breath of wind disturbed the treetops in the Forbidden Forest; the Whomping Willow was motionless and innocent-looking. [cut]
       Harry set down his goblet and was about to turn back to his bed when something caught his eye. An animal of some kind was prowling across the silvery lawn.
       Harry dashed to his bedside table, snatched up his glasses, and put them on then hurried back to the window. It couldn't be the Grim -- not now -- not right before the match -
       He peered out at the grounds again and, after a minute's frantic searching, spotted it. It was skirting the edge of the Forest now ... It wasn't the Grim at all ... it was a cat ... Harry clutched the window ledge in relief as he recognized the bottlebrush tail. It was only Crookshanks ...
       Or was it only Crookshanks? Harry squinted, pressing his nose flat against the glass. [PoA ch. #15; p. 223/224]

[cut] Harry got up very quietly and moved across to the window beside Neville's bed, and stared out on a truly glorious morning. [cut] Directly ahead of him, Harry could see the towering beech tree below which his father had once tormented Snape. [cut]
Something caught Harry's attention: movement on the edge of the Forbidden Forest. [cut] As Harry watched, Hagrid staggered to the door of his cabin and disappeared inside it. [OotP ch. #29; p. 581]

This is actually somewhat problematic because we want the Tower to be at the front of the castle, to make it as close to the Forest as we can get it in order to reduce the distance over which Harry could distinguish Crookshanks in half light. But if the Tower is at the front of the castle it must be in between the beech tree and Hagrid's cabin, making it difficult to see both from the same window. There's also the problem of Harry looking towards Hagrid's cabin - which is definitely broadly west - in the early morning and having to squint against the sun. The simplest solution I can see is that on the occasion when he was looking at the beech tree he actually opened the window and stuck his head out, enabling him to see Hagrid's house as well by looking to the side, and he was squinting because he had accidentally looked straight at the sun while contemplating the beech tree, and so he had purple spots before his eyes.

There is no way you can have a single window from which you can look straight ahead and see the beech tree and also see the Whomping Willow, which is in exactly the opposite direction, unless that window wraps right around the tower: so we must assume that when Harry looked at the Willow he was looking from a window on the far side of the room relative to the one which overlooks the beech tree. Note also that because Gryffindor Tower is on the south side of the castle, He let them all leave in threes and fours, watching their tiny dots anxiously to see that they returned safely to their dormitories: the Hufflepuffs to the basement corridor that also led to the kitchens; the Ravenclaws to a tower on the west side of the castle, and the Gryffindors along the corridor to the Fat Lady's portrait. [OotP ch. #18; p. 351] plus the Willow is to the north and the west wing projects out to the side, Harry would be looking down from the top of Gryffindor Tower towards the Willow either acroos or just to one side of the top of the Charms section, and further away the west wing and the block where Flitwick's office is, and he would see the West Tower and Owlery sticking up close to the tree.

The location of Ravenclaw Tower is less well-established, but it's somewhere vaguely in the vicinity of the west wing, as is the West Tower. a.k.a. the Owlery.

Working notes

Because sorting out the castle is such a massive task, and could take years more (writing as at summer 2014) to finish, I am going to go ahead and post my working notes here, and a crude one-storey-fits-all plan of the castle. At some point later I will go back and insert all the quotes which show where these notes come from, and work out the castle floor by floor - but this should give readers something to go on meanwhile. 'I think the feast's already started,' said Ron, dropping his trunk at the foot of the front steps and crossing quietly to look through a brightly lit window. 'Hey, Harry, come and look -- it's the Sorting!'
Harry hurried over and together, he and Ron peered in at the Great Hall. [CoS ch. #05; p. 60/61]

Harry, Ron and Hermione slipped and slid across the Entrance Hall and through the double doors on the right, [cut]
[cut] The four long house tables were packed with chattering students; at the top of the Hall, the staff sat along one side of a fifth table, facing their pupils. It was much warmer in here. Harry, Ron and Hermione walked past the Slytherins, the Ravenclaws and the Hufflepuffs, and sat down with the rest of the Gryffindors at the far side of the Hall, [GoF ch. #12; p. 153/154]

Harry wondered whether he could slip his Invisibility Cloak back on, thereby gaining his seat at the long Gryffindor table (which, inconveniently, was the furthest from the Entrance Hall) without being noticed. [HBP ch. #08; p. 154]

Bear in mind that in the U.K. the "first floor" is the first floor above the ground floor, so that e.g. a house whose top storey is described in the U.K. as the "second floor" is three storeys high. We know that the body of the castle is eight storeys high (it has a seventh floor, and no higher floor is mentioned other than in the various towers), and from the length of time it takes to get around it it must be hundreds of yards long. It's also quite thick through the middle, not long but very narrow.

We know this because we can see from JKR's own drawing that the main entrance is on one of the long faces of the castle. We know that you can see into the Great Hall while standing on the lawn at the front of the castle, near the entrance, so one wall of the Great Hall forms part of the same front wall of the castle as the main entrance. We also know that when you go in through the main entrance you find yourself by a door which lets into the side-wall of the Great Hall to your right - close to one end of it, but almost certainly not actually in the end wall of it, because the Trio come in through the door and then have to walk crosswice across all the tables to reach Gryffindor on the far side. The long axis of the Great Hall is therefore at right angles to the front wall of the castle.

...they walked out of the chamber, back across the hall and through a pair of double doors into the Great Hall.
Harry had never even imagined such a strange and splendid place. It was lit by thousands and thousands of candles that were floating in midair over four long tables, where the rest of the students were sitting. [cut] At the top of the hall was another long table where the teachers were sitting. [PS ch. #07; p. 87]

Things started to go downhill from breakfast in the Great Hall. The four long house tables were laden with tureens of porridge, plates of kippers, mountains of toast and dishes of eggs and bacon, beneath the enchanted ceiling [CoS ch. #06; p. 68]

[cut] the three of them made their way back down the marble staircase to the Great Hall.
It was a sea of pointed black hats; each of the long house tables was lined with students, [cut]
[cut] Professor McGonagall strode off towards her empty seat at the staff table, and Harry and Hermione set off in the other direction, as quietly as possible, towards the Gryffindor table. [PoA ch. #05; p. 71]

The four long house tables were packed with chattering students; at the top of the Hall, the staff sat along one side of a fifth table, facing their pupils. It was much warmer in here. Harry, Ron and Hermione walked past the Slytherins, the Ravenclaws and the Hufflepuffs, and sat down with the rest of the Gryffindors at the far side of the Hall, [GoF ch. #12; p. 153/154]

Tiny Dennis Creevey staggered forward, tripping over Hagrid's moleskin, just as Hagrid himself sidled into the Hall through a door behind the teachers' table. [GoF ch. #12; p. 158]

Hagrid sidled into the Hall through a door behind the staff table twenty minutes after the start of the feast. [GoF ch. #16; p. 222]

'Well, the Goblet is almost ready to make its decision,' said Dumbledore. 'I estimate that it requires one more minute. Now, when the champions' names are called, I would ask them please to come up to the top of the Hall, walk along the staff table and go through into the next chamber' -- he indicated the door behind the staff table -- 'where they will be receiving their first instructions.' [GoF ch. #16; p. 236]

Harry saw Viktor Krum rise from the Slytherin table, and slouch up towards Dumbledore; he turned right, walked along the staff table and disappeared through the door into the next chamber. [GoF ch. #16; p. 237]

When Fleur Delacour, too, had vanished into the side chamber, silence fell again, [GoF ch. #16; p. 237]

Every single Hufflepuff had jumped to his or her feet, screaming and stamping, as Cedric made his way past them, grinning broadly, and headed off towards the chamber behind the teachers' table. [GoF ch. #16; p. 238]

Harry moved off along the teachers' table. Hagrid [cut] looked completely astonished, and stared at Harry as he passed, like everyone else. Harry went through the door out of the Great Hall, and found himself in a smaller room, lined with paintings of witches and wizards. A handsome fire was roaring in the fireplace opposite him. [GoF ch. #17; p. 240]

Harry finished his breakfast in the emptying Great Hall. He saw Fleur Delacour get up from the Ravenclaw table and join Cedric as he crossed to the side chamber and entered. Krum slouched off to join them shortly afterwards. Harry stayed where he was. He really didn't want to go into the chamber. [cut] the door of the side chamber opened, and Cedric stuck his head out. [GoF ch. #31; p. 534]

'It's great being back here,' said Bill, looking around the chamber (Violet, the Fat Lady's friend, winked at him from her frame). [GoF ch. #31; p. 535]

The four long house tables in the Great Hall were filling up under the starless black ceiling, [OotP ch. #11; p. 182]

Harry did not understand what she was talking about but did not ask; his attention had been caught by Professor Grubbly-Plank who had just appeared behind the staff table; she worked her way along to the very end and took the seat that ought to have been Hagrid's. [cut]
[cut] The first-years lined up in front of the staff table facing the rest of the students, and Professor McGonagall placed the stool carefully in front of them, [OotP ch. #11; p. 184]

The terrified-looking boy Harry had noticed earlier stumbled forwards and put the Hat on his head [OotP ch. #11; p. 187]

The fifth-years ate lunch with the rest of the school (the four house tables had reappeared for the lunch hour), then they trooped off into the small chamber beside the Great Hall, where they were to wait until called for their practical examination. As small groups of students were called forwards in alphabetical order, those left behind muttered incantations and practised wand movements, occasionally poking each other in the back or eye by mistake. [OotP ch. #31; p. 628]

The Great Hall, with its four long house tables and its staff table set at the top of the room, [HBP ch. #08; p. 154]

[cut] Professor McGonagall, who was speaking from the raised platform at the top of the Hall. [DH ch. #31; p. 489]

[cut] necessitating Professor McGonagall’s descent from the teachers’ platform [cut]
[cut] Kingsley had stepped forwards on the raised platform [DH ch. #31; p. 491]

[cut] students flooded the platform [DH ch. #31; p. 492]

The injured were being treated up on the raised platform [DH ch. #33; p. 530]

They moved Voldemort’s body and laid it in a chamber off the Hall, [DH ch. #36; p. 596]

There are nearly seven hundred students (see Population and Pupils for how we know this) who sit on either side of four long tables, so each table is long enough to seat around eighty-five people on each side, plus there is space to pass easily at either end of the tables, and a dias at one end which holds another, crosswise table, space to sit at it and then space to pass easily behind it, and then there's a smallish room behind that. In fact if it's the same as the "small chamber beside the Great Hall" where Harry's year waited to be called for their Charms practical exam, it's not as small as all that, since the entire year - around fifty students - fit into it at once and have room, just, to practice spells.

Between the long tables and the teachers' dias there is enough space for the first years to line up abreast with the Sorting stool in front of them and then walk forwards to sit on it, so at least about ten feet. If we allow two feet of space per diner, the Great Hall is probably around sixty-six yards long, plus the room beyond it and the thickness of the wall in between them, and its long axis passes through the breadth rather than the length of the castle. So, we know from JKR's drawing that the castle is longer in the direction at right-angles to the Great Hall than it is parallel to the Great Hall, but we also know that the direction parallel to the Great Hall is at least about seventy-five yards long.

If the vast area which this eight-storey building covers was more or less a solid block - even one with a central courtyard - it would be ridiculously large to accommodate a medium-sized school: it would give every student and staff-member around two thousand square feet of space each, or the equivalent of about a five-bedroom house - and that's without factoring in the dungeons and basement, whose extent is unknown, and the extra space in the towers. Also, most of the corridors and classrooms seem to have windows to the outside, which limits how thick through each block of buildings can be, unless the rooms are the size of aircraft hangars or most of the windows are artificial.

I think it safe to assume, therefore, that the area enclosed within the boundaries of the castle is not covered with a few vast solid blocks of buildings, but with a series of variously-sized buildings joined by a tracery of walls and covered walkways enclosing a lot of open space, enabling a series of corridors and classroom-sized rooms to have windows.

We know that Gryffindor Tower is towards the southern end of the castle because it is close to the beech tree, whose position has been established in the article on the castle grounds. Half way between the Gryffindor common room and the library Harry encounters Filch, who has just come from the Entrance Hall, so the Entrance Hall itself is roughly half way in between the library and Gryffindor Tower. The library therefore is somewhere north of the Entrance Hall and about as far from it as Gryffindor Tower is south. It is also fairly near Dumbledore's office. Since it is so central to the school you would expect it to be in the main block (whereas it is not unreasonable for the hospital wing to be in an outlying bit because of the risk of infection).

Running away from the library, Harry pursues a wild course in the dark and ends up back near his starting point: he encounters Snape and Filch saying he can't have got far from the library, therefore they are unlikely to be far themselves. Yet, the following day it takes Harry nearly an hour to work out where he was. This suggests that even the main block of the castle is very complicated, which argues against there being a single, simple large courtyard. [It also suggests that after seeing his parents in the Mirror of Erised on the first night, Harry was so dazed he ambled back to the common room on autopilot and didn't notice what route he was going.] Another point is that the corridors may well be interrupted by doors, to limit draughts, and Harry had trouble finding where he had been because he couldn't distinguish the door to the corridor from the doors to nearby classrooms. When Harry chases after the Grey Lady we are told that there is a door at the start of the corridor down which she has drifted.

The hospital wing is near Dumbledore's office, which is on the opposite side of the castle from the RoR, which is near the top of the marble stairs, and on the far side of the Astronomy Tower relative to those stairs. Note there must also be some private rooms in the hospital wing.

We know Flitwick's office is on the right (broadly east) of the West Tower as you face that part of the building. Snape and Fudge leave Flitwick's office and pass the West Tower heading for the hospital wing. Harry and Hermione go the other way by a fairly roundabout route to the hospital wing, taking ten minutes to get there (which does include some stairs and a pause to avoid Peeves). Yet, seen from the outside the hospital wing is close enough to Flitwick's office that someone in the hospital wing can hear a shout coming from the office. This suggests that hospital wing and the west block where Flitwick's office is are quite close together but there is no direct, short route from one to the other, so they may be separated by open ground.

Justin and Nearly Headless Nick are found Petrified in a corridor fairly near (but higher up than) the library and are taken from there to the hospital wing. McGonagall and Harry turn a corner en route and instead go to the Head's office.

Nick and Justin are taken up apparently to the seventh floor in order to get to the Hospital wing, and other evidence suggests that the hospital wing is two floors higher than the top of the marble stairs. Yet, we are told there are classrooms opening onto corridors both above and below the hospital wing, and Harry has to go up in order to reach the floor below Myrtle's bathroom which is no higher than the second floor.

Maybe there is a spur of rock interrupting the wall and meaning that you have to go up and pass above it, on the seventh floor, to get to the main building - or the wall here is just a high wall and has a passage only along the top.

Maybe the ground the castle stands on undulates so much that the seventh floor in the West Wing is the first floor in the main building. Even if ceilings in the West Wing are lower that requires a height difference of 70ft.

Or - there's a passage through at the seventh floor and a low one.

Let's say the fourth floor (about) in the main building is the seventh floor in the West Wing. Then the hospital itself is on high ground relative to the corridor, which is the top of the wall covered in. You come out of the middle of the hospital wing into the top of the walkway, walk round to the left, go up stairs into the top floor of the West Wing, then they have to go downstairs again to the first floor to get into the main building. Maybe all the upper floors in the bit between the West Tower and the main building are offices and you can only get through on the first floor? No - McGonagall took Nick and Justin through on the sixth floor. But maybe to get in to Gryffindor Tower you need to start low down?

There are blocks of classrooms either side of the hospital wing, because people keep making excuses to pass by it and look at Hermione. The fact that Harry hears people disgorging into corridors above and below the hospital wing suggests that it is attached to a block of classrooms - it's not just that there are classrooms above and below the ward itself. The reason is that if the corridor leading to the hospital wing was a passage along a wall, with nothing above or below it, people in classrooms above or below the ward would all have to climb up or down stairs to get to the passage out, exactly at that point, and what Harry would hear would primarily be footsteps on stairs. So there must be a multi-storey block of rooms opposite or either side of the ward (opposite is probably better because it allows the ward to have more windows), each block with its own corridor, and Harry hears people clattering away into a distance where they will probably climb stairs he cannot hear. This block must be north or south of the hospital wing, or if east or west then it occludes only one end of the ward, because we know both the dawn and sunset sun shines into the ward, so there cannot be a building which is taller than the hospital ward and both parallel and close to it, and which is east or west of it.

The ward is not on the top floor and yet catches the early morning sun, so there must not be any tall walls very close to it.

Dumbledore's office is at top left of the Marauder's Map, or at least in the top-left quadrant. It seems to be possible to get from Dumbledore's office to the hospital wing down a simple stair, yet the public entrance to Dumbledore's office is up a side-turning as you approach the hospital and apparently well before you arrive. Dumbledore's gargoyle door is in the middle of a corridor, not at the end of one, and that corridor is on the seventh floor. It cannot be the case that the far end comes out nearer to the hospital, otherwise the party carrying Nick and Justin would have turned off there, and it can't represent an obvious short cut to the hospital from another direction or you have to ask why Snape and Fudge went round the long way. It is unlikely that when they were conveying Nick and Justin they passed both ends of the gargoyle corridor before McGonagall decided to turn off. It can't result in a block of eight-storey building close to the hospital on the east or, probably, the west side, because the dawn light has to be able to shine into the ward which is not on the top floor, and moonlight shines in from such a low level that it stripes the ceiling. The Head's tower cannot be too far out in the wilds because Harry can sprint from the Head's office to Gryffindor Tower, up to his room, back down and to the Entrance Hall in five minutes.

Some leeway exists in the idea that the gargoyle corridor might actually be carried in a bridge, so sunlight can get onto the hospital wing underneath it, or that it passes horizontally close to the hospital wing but on a different vertical level and there is no public stair nearby to link them.

I have posited therefore that the Head's tower is joined on to the end of the hospital wing. Public approach to the gargoyles is along a passage brancing off the West Wing: following the West Wing around leads to the public door to the hospital wing. There are stairs leading up the front and side of the Head's tower, inside turrets. The front one is the one up from the gargoyles. The side one joins several floors of rooms where the head lives and then comes out in Poppy Pomfrey's office, which is a slice through the tower. The internal stair then continues down to the lower floors of the tower where Poppy lives, and there is an external stair which they can both use and which leads down to an enclosed corner of garden called the Physick Garden and Headmaster's Pleasaunce.

If the hospital is where I have placed it there would be quick access for casualties from the Forest, the Quidditch Pitch and the loch, for they could come to the front lawn, in through the pend which leads to the broomshed, and straight up some sort of lift to Poppy's office. Say that there are two turrets running up the side of the head's tower. One is for internal use: it runs down from Albus's office to Poppy's office, connecting his rooms to each other, and then down to the ground connecting Poppy's rooms. One runs up the tower for public access - inside the wall which joins the head's office to the West Wing, if that is solid and not an open bridge. Above Poppy's office it continues on up to become the headmaster's official stair (interrupted by a ceiling).

That would make this emergency access also near the steps down to the harbour, which might give rapid access from the dungeons too. The top of the steps to the harbour is either on the front lawn or tucked into the enclosed area near the broomshed.

Myrtle's bathroom is sometimes on the first and sometimes on the second floor.

On the seventh floor Snape runs from the Astronomy Tower and Harry sees him turn a corner at the end of the corridor (which must be quite wide, as several people are fighting in it). Harry follows thinking he is going to the RoR, then turns off down the stairs before reaching the RoR.

The RoR is near the marble stairs and on the hospital or northern side, because walking from the hospital you pass the RoR before reaching the stairs. It seems to be at right angles to the front of the building and near a window which looks out at the front, because standing near it Harry can see out of a window which looks down towards the outside of the building on the landward side, and just round the corner from the RoR is a corridor which is blown open during the battle and which pretty-much has to be either on the front (western) or northern side of the building. We know this because the eastern side of the castle faces onto the cliff-edge, and the southern end has quite a sharp drop as well (because the fateful beech tree is close to the castle but also considerably below it), so the front lawn, west wing and northern battlements are the only sides where the attackers may be able to get fairly close to the building. Internal evidence to do with distances and lines of sight, how far the West Tower needs to project from the front face in order for Flitwick's office to be thirteen windows right of it and how far north of the main doors this western extension needs to be in order to still allow the sun to shine in through the main doors, indicates that the northern battlements and even the West Tower are a considerable distance from the marble stairs, so the blasted-open corridor round the corner from the RoR cannot be there: it must be on the front, west-facing face of the castle, so the RoR (which is in a corridor round a corner from the one which was blasted open) is in a corridor at right-angles to the front, and on the left (north) of the main doors as you face them.

The Astronomy Tower is so close to the main doors that it has an overhang which is actually above them. Weak evidence suggests that it is on the right or south side of the main doors: coming up from near Hagrid's house Harry and Hagrid seem to turn to reach the Astronomy Tower before coming to the doors. Also, if it is on the right of the doors it slightly interferes with the view from the main doors to the gates, but if on the left it severely interferes with the view from the bike shed to the doors.

From the Astronomy Tower Harry pursues Snape along a corridor, and rounds a corner heading towards the RoR, where he sees a footprint which shows somebody was heading for the stairs not the RoR - and this seems to be before not after actually reaching the RoR, so it's not that he reaches the RoR and then sees a footprint going on past it. He then rounds another corner to the top of the marble stair. He did not go along the front of the building and then right and right to get to the head of the stair, because in that case he would have passed the RoR before reaching the stair, so he must have gone straight ahead at right-angles to the front face of the building, then turned left, then seen a footstep bearing left again towards the stairs and turned to follow it. That means that when he sets out from the Astronomy Tower he is running down a corridor which is heading in the same direction as the long axis of the Great Hall, and then he sees Snape turn left at the end of that corridor in order to get to the marble stairs: i.e. the corridor terminates at a point somewhere along the length of the Entrance Hall, either above the hall or alongside it.

The marble stair seems to reach higher as the series progresses. This could be magic or it could mean that the fancy stair is a fairly new addition which is slowly being extended as and when the school can afford it.

Heading from the Entrance Hall to the North Tower they come into a north-south passage from the west and partway along. There must be a reason why picking up the passage at its southern end would involve a longer loop. This confirms that there isn't a corridor which simply runs back across the top of the Great Hall.

It is common for castles to start with a tower on a mound and then spread outwards, so I have given Hogwarts an Old Keep with four towers, to the north of the main body of the castle.

The reason I have put the room behind the teachers' table at the back of the Great Hall into the base of a separate, projecting block is this. We know that the front of the castle where the main doors and Entrance Hall are faces at least broadly west and that the long axis of the Great Hall is more or less at right angles to the front of the castle, so the long axis of the Great Hall runs broadly east-west. We also know that the teachers' table is at the far end of the Great Hall relative to the Entrance Hall of the castle, so the teachers' table is at the east end of the Great Hall. The rising sun shines into the Great Hall so there must be windows behind the teachers' table, yet there is also a room there.

Assuming the windows are real and that the room isn't in Wizard Space there are two ways round this. There is a window or windows which come down near the floor but they are offset to one side, allowing for a solid, filled-in section from floor to ceiling at one side of the hall where the back room is, or the solid extension where the room is is only single-storey and the windows begin above it. I have decided on the former because there is a description of banners hung on the wall behind the teachers' table, suggesting a high solid block of wall. However this back room is constructed, there is another way into it - Molly Weasley arrives in the room without apparently going through the Great Hall, and we see Hagrid come into the Hall by the door of this room, which suggesats it may open to the outside. I have given it a door into my notional teachers' garden, which can be accessed from the outside by walking around the back of the castle, above the loch.

The dungeons must have more than one exit, for safety reasons - there really *must* be a way out down as well as up. There must be a second way out of the Hufflepuff cellars, as well - maybe they communicate with the dungeons, or maybe one or more of the "secret" tunnels is a back door from the cellars or dungeons.

I make Hogwarts about 450 by 200 yards - comparable with Windsor Castle which is 600 by 150 yards.

Coming from History of Magic they have moved horizontally through corridors, plural, as well as up stairs, to turn round a corner into a corridor which is above but quite near the Entrance Hall.

History of Magic is on same floor as Myrtle. They are going along a main corridor towards History of Magic, then they go down a side passage which takes them towards Myrtle.

Coming up from History of Magic Harry walks into McGonagall halfway down the stairs, having come from the common room.

Leaving the History of Magic classroom, Harry goes along a corridor until he is out of sight of it. Here he comes to a window through which he can see Hagrid's cabin. He then goes downstairs to reach the staff room. The staff room door has a stone gargoyle on either side.

The library is not more than five minutes' walk from Moaning Myrtle's bathroom.

Coming from the hospital wing, from the ward where Hermione was, towards the common room they pass near Myrtle's bathroom, which is one floor up and round a corner from them.

From the DADA office they go downstairs and along a corridor to reach Myrtle's bathroom.

From Myrtle's bathroom they go along a corridor and rapidly find themselves at McGonagall's office.

The humpbacked witch statue is on the third floor, on or near a route between the Entrance Hall and Gryffindor Tower.

DH 497-500 During the battle, Harry goes from the Entrance Hall and sets off down a corridor where Hagrid arrives through an outside window which looks into the grounds - so this must be the front face. He passes the staff room and reaches the end of the passage. From here he speeds off down a corridor lined with portraits. He runs on through passages plural, round a corner to where there is a hole previously guarded by a statue - is this the Hump-Backed Witch or Gregory the Smarmy? Can't be Gregory, who is in the East Wing, but not the HBW either because it's ground floor. Must be one of the three unspecified tunnels. Along another corridor and he runs into owls - but this can't really be near the owlery because he's on the ground floor. Round another corner he meets Ron and Hermione having come from the Chamber of Secrets, and here they are near the second entrance to the RoR.

The DADA office commands views of the middle of the loch and of the Quidditch pitch, yet is a long way from the East Wing, and on the right (south) of the doors. So the East Wing must be to the north.

I have separated the west wing from the block where Flitwick's office is by a short stretch of wall, because we are told that when they climb down the West Tower there is a corridor which leads "towards" the west wing.

The third-floor corridor on the right is presumably to the right of the entrance, and therefore either over or to the right of the Great Hall. I have ended up with it not serving any major purpose, but that makes sense because they wouldn't want to block off a major thoroughfare. I have explained the fact that it takes a very long journey to get from the Entrance Hall to Gryffindor Tower in Harry's first year but seems to take less time later by saying that the shorter route to Gryffindor Tower runs through part of the third-floor corridor on the right, and was blocked off during first year.

[OotP ch. #13; p. 227] Here Harry looks out of a window as he turns into the Fat Lady's corridor, and sees Hagrid's cabin. This works if he is coming by the short route via the third-floor corridor right.

Leaving Charms, the door to the third-floor corridor right is at the end of the corridor they are in and they run into the door, suggesting it is continuous with the corridor leading out of Charms. I suggest it is a covered-over walkway along the top of a wall, so that when they lift the trapdoor there are no rooms underneath: they descend through the height of the wall into chambers inside the mound the castle stands on. The wall may not be as much as four storeys high at that point, but still, they drop the height of the wall from the floor of the third floor and then at least a storey into the mound - more, maybe, because there needs to be a self-supporting thickness above them. They probably drop around 50ft.

Note that Moody can see the topmost sail of the Durmstrang ship [GoF ch. #29; p. 496] from his classroom, but a mast can be very high : the Japanese four-masted sailing barque the Kaiwo Maru has an overall mast height of 182ft. This does seem to be unusually tall, though, so we don't want the Durmstrang ship to go much over that.

Even allowing for a drop of about 60ft to water level, the mast may well be visible from any upstairs window which has a line of sight over lower roofs: the classroom does not have to be on an outer face of the building. I have made it so that the line of sight passes over the top of the Great Hall, which is not full height. However, it also needs to pass over the corridor leading to the Charms section, north of Gryffindor Tower.

The DADA classroom is at least about 200 yards from the ship, even if we bring the curve of the lake round a bit. Say the ship is 180ft tall or 60 yards. The classroom will have to be on the 5th floor to see the very top of the mast, unless the cliff is less than 60ft high or the mast is much more than 180ft high or the wall is a lot less than eight storeys or the wall is lower because it is draped along a descending slope of rock. If we assume a 10ft different in base height between the wall and the main body of the school we can have the cliff 70ft at the centre and the DADA classroom as low as the 4th floor. All this assumes that what Moody sees is not the whole of the top sail but just the tip of it.

If on the other hand Charms is only four storeys high - we know it's at least that because Harry's Charms classroom is on the 3rd floor - then the DADA classroom could be lower. We're actually told it's on the 3rd floor, the same level as the minimum height of Charms.

If the Charms and DADA office stand at the same level, then even if Charms goes no higher than the 3rd floor Moody's view would be angled up, because he has to see from the window of his classroom over the roof of a class at the same height. For Moody to see the mast over it at all Charms, or at least the corridor leading out of it, has to be slightly lower, meaning it is going down a slope relative to the main body of the castle. If we assume the 120ft cliff and the body of the castle 10ft higher than Charms, then the Charms section needs to go no higher than the third floor. This makes sense because when Harry and co. flee along the Charms corridor they end up in the third floor corridor right. It may be that a lot of the buildings are accessed on the third floor - it would explain why the third floor is searched particularly for Sirius. Or perhaps the stairs have been told not to let him pass, trapping him on the third floor.

It is said that Dumbledore's study is at top left of the Marauders' Map. However, we know Dumbledore's study is close to the hospital wing, which is close to Flitwick's office, yet the castle must extend a long way further in order to have a North Tower. So I've settled for it being in the top left quarter. Similarly Snape's office is said to be at bottom left but we know it's under the Entrance Hall, which puts it only in the bottom left quarter.

The DADA office is on the ground floor in GoF, 3rd floor in OotP. Myrtle's loo moves from first to second floor.

The stair with the trick step, behind the tapestry, is on a route between the Great Hall and Gryffindor Tower. Starting from the Prefects' bathroom Harry heads away from Gryffindor Tower and comes to this stair. Harry has gone through at least two corridors, both illuminated by moonlight so with windows on the same side, to get from the common room to the Prefects' Bathroom.

Charms is on the right of the main door, because it leads to the third floor corridor right, yet you can see the front door, past the Astronomy tower. Of course the Astronomy tower, which has a parapet, may be fairly narrow. Even so, if the Astronomy tower is on the right - which it really has to be, because we know the Room of Requiremnt is close to the marble stairs and on the hospital or left side of them (we know the hospital wing is to the left because Harry and Hermione get to it by going further west or north from the West Tower), and the Astronomy Tower is close to the marble stairs and yet several corners from the RoR - then Charms must stick out a long way. Maybe it sits on an outcrop of rock - or maybe it sits on an arcade/cloister. Indeed, it must stick out in front of the Great Hall, so it would have to be open underneath to let light in.

The Charms corridor may well extend above the top of the Entrance and Great Hall and out to the right, but part of it still needs to stick out far enough to see past the Astronomy Tower, which we know really *is* a tower, i.e. it goes all the way to the ground. It makes sense if Charms is on a single or double-storey balcony - so that there doesn't need to be a projection at ground level where it would interfere with lines of sight from the doors (we already know it doesn't extend up to the whole height of the castle because it has to be possible to see over it and see the mast of the Durmstrang ship).

[DH ch. #31; p. 499/500] suggests a back way down to the greenhouses.

The DADA office is on the second floor. To get from there to Myrtle's bathroom you go down a stair and along at least one corridor. It's near Charms. It seems to be one corridor away from the marble stairs. Between the DADA office and the Fat Lady, Harry climbs a stair to the seventh floor and turns right. It commands a view of the Quidditch pitch, and of the Forest. Near the DADA office is a stair down to the first floor. A person coming down it has a window behind them leading to the grounds. It faces into a corridor which has an open door at one end, beyond which is another stair to the second floor. As you come up the marble stair the DADA office is on your right. There is an "either end" to the corridor the DADA office is on, so it's in the middle.

If the Entrance Hall is double-height, the second floor is the first upper floor the stairs arrive at and they may well face the other way at that point.

Transfiguration is a long way from the North Tower and a long way from the DADA office.

Leaving the DADA classroom, Harry goes halfway along a corridor, then hears a racket which is at a distance (in the east wing) and at a higher level. Heading in the opposite direction, broadly west, he comes to the DADA office. It is on a corridor in which there is a large suit of armour with a helmet. It stands some distance from the office, and has enough space behind it to hide in. The brooms are chained to the wall below the kitten plates. By the fireplace - probably on the mantelpiece if any - there is a box of Floo powder. There is a grate full of neatly-stacked logs.

Plan of Hogwarts castle

Bear in mind that this is a crude, working aerial view which throws everything into one basket, but in practice not every feature will be present on every floor. There are turrets, for example, which do not go all the way down to the ground, and possibly corridors directly above at least part of the Great Hall. At some point I will work it out floor by floor but that's going to have to wait.

For sound canononical reasons which will be explained later, both the North Tower and the Astronomy Tower have a long thin column topped by a wider, overhanging top. In the case of the Astronomy Tower this top is open to the elements, but the North Tower is covered by some sort of onion dome.

I have constructed Gryffindor Tower with a wide circular base, containing the common room, topped with three thinner turrets arranged in a trefoil shape. This is to enable boys and girls in each year to occupy circular dorm rooms which each take up a whole floor of a tower/turret, without having to have fourteen storeys of dorms. One turret contains four upper storeys of boys' dorms and one base storey of boys' lavatories and showers; one turret contains four upper storeys of girls' dorms and one base storey of girls' lavatories and showers; and the third turret contains three storeys of girls' dorms and three of boys', alternating. Thin colums containing the boys' and girls' stairs run up the angles between the larger turrets, so that each stair opens onto one set of lavatories and showers, four rooms in a single-sex turret and three rooms in the mixed-sex turret.

3CR 3^rd-floor corridor right

AT Astronomy Tower

BS broomshed

CC Charms corridor

Ch chapel

DC3 DADA classroom (3^rd year)

DC4 DADA classroom (4^th year)

DO DADA office

EH Entrance Hall

EW east wing

FO Flitwick's office

GH Great Hall

GT Gryffindor Tower

GtS Gregory the Smarmy statue

HBW humpbacked witch statue

HO Head's Office

HoM History of Magic classroom

HW hospital wing

L library

McGO McGonagall's office

McGQ McGonagall's quarters (in base of Gryffindor Tower)

MM Moaning Myrtle's bathroom

MoE Mirror of Erised

NB North Battlements

NT North Tower

PB prefects' bathroom

RoR Room of Requirement

RT Ravenclaw Tower

SC Sir Cadogan's portrait

SR staff room (under library)

SS swivelling stair

T? tunnel behind unknown statue

TC Transfiguration classroom

TR Trophy Room

TS trick stair

WG water gate/tunnel

WT West Tower/Owlery

WW west wing

Dots mark the route Snape follows from the Astronomy Tower round to the main stair at the end of HBP.

I've included a non-denominational, adaptable chapel because you would expect there to be one, for the benefit of students or staff who are religious, but since Harry never mentions it I've put it out of the way at the base of the North Tower.

3CR	3^rd-floor corridor right
AT	Astronomy Tower
BS	broomshed
CC	Charms corridor
Ch	chapel
DC3	DADA classroom (3^rd year)
DC4	DADA classroom (4^th year)
DO	DADA office
EH	Entrance Hall
EW	east wing
FO	Flitwick's office
GH	Great Hall
GT	Gryffindor Tower

GtS	Gregory the Smarmy statue
HBW	humpbacked witch statue
HO	Head's Office
HoM	History of Magic classroom
HW	hospital wing
L	library
McGO	McGonagall's office
McGQ	McGonagall's quarters (in base of Gryffindor Tower)
MM	Moaning Myrtle's bathroom
MoE	Mirror of Erised
NB	North Battlements
NT	North Tower

PB	prefects' bathroom
RoR	Room of Requirement
RT	Ravenclaw Tower
SC	Sir Cadogan's portrait
SR	staff room (under library)
SS	swivelling stair
T?	tunnel behind unknown statue
TC	Transfiguration classroom
TR	Trophy Room
TS	trick stair
WG	water gate/tunnel
WT	West Tower/Owlery
WW	west wing