Från artikeln "Harry Potter Filming Locations in Britain" på Rick Steves webbplats: (för de av er som kanske inte vet är Rick Steves en amerikansk författare och tv-personlighet som fokuserar på europeisk resa - han hade en långvarig reseshow på PBS).

Platser i Oxford:

Hogwarts, Harry’s prestigious wizarding prep school, is a composite of several locations, many of them real places in Oxford.

Christ Church College inspired two film sets familiar to Potter fans. In The Sorcerer’s Stone, the kids are ferried to Hogwarts and then ascend a stone staircase that leads into the Great Hall. Christ Church’s high-ceilinged dining hall was a model for the one seen throughout the films (with the weightless candles and flaming braziers).

Christ Church College matsal

Hogwartsmatsal:

Christ Church College, inspiration till storalen:
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Later in The Sorcerer’s Stone, Harry sneaks into the restricted book section of Hogwarts Library under a cloak of invisibility. This scene was filmed inside Oxford’s Duke Humfrey’s Library. Hermione reads about the Sorcerer’s Stone here, too.

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At the end of The Sorcerer’s Stone, Harry awakens in the Hogwarts infirmary, filmed in the big-windowed Divinity School, on the ground floor of the Bodleian Library; Ron also recuperates here after being poisoned in The Half-Blood Prince. In The Goblet of Fire (2005), Mad-Eye Moody turns Draco into a ferret in the New College cloister.

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Platser i Durham och nordöstra England

In The Sorcerer’s Stone, Harry walks with his white owl, Hedwig, through a snowy cloister courtyard located in Durham’s Cathedral.

Harry first learns to fly a broomstick on the green grass of Hogwarts’ school grounds, filmed inside the walls of Alnwick Castle, located 30 miles from Newcastle. In The Chamber of Secrets, this is where the Weasleys’ flying car crashes into the Whomping Willow.

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PlatseriSkottland

Also in The Prisoner of Azkaban, Hogwarts Lake was filmed using Loch Shiel, Loch Eilt, and Loch Morar near Fort William, and Hagrid skips stones across the water at Loch Eilt. Steal Falls, a waterfall at the base of Ben Nevis, is the locale for Harry’s battle with a dragon for the Triwizard Tournament in The Goblet of Fire.
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PlatseriochruntBath

Many scenes showing the mysterious side of Hogwarts were filmed in the elaborate, fan-vaulted corridors of the Gloucester Cathedral cloisters, 50 miles north of Bath. In The Sorcerer’s Stone, when Harry and Ron set out to save Hermione, they look down a long, dark Gloucester hallway and spot a 20-foot troll at the far end.

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In The Sorcerer’s Stone, the scene showing Harry being chosen for Gryffindor’s Quidditch team was shot in the halls of the 13th-century Lacock Abbey,13 miles east of Bath. Harry attends Professor Snape’s class in one of the Abbey’s peeling-plaster rooms — appropriate to Snape’s temperament. (You can visit with recommended Mad Max Tours.)

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Outdoor scenes from the first Deathly Hallows, in which Harry, Ron, and Hermione take refuge in the woods, were filmed in the Swinley Forest area of Windsor’s Great Park.

Från wikipedia :

• Alnwick Castle, Northumberland (Hogwarts exterior)
• Bodleian Library, Oxford (Hogwarts interiors)
• Christ Church, Oxford (Hogwarts interiors)
• Durham Cathedral (Hogwarts interiors)
• Gloucester Cathedral (Hogwarts corridors)
• Harrow School, (Professor Flitwick's classroom)
• Lacock Abbey, Wiltshire (Hogwarts interiors)
• New College, Oxford (Hogwarts cloisters)
• St Paul's Cathedral, London (Spiral staircase in Hogwarts)