While the majority of the exterior shots were filmed at Alnwick Castle, other locations were also used:
* Durham Cathedral was used for some of the interior shots, especially the Great Hall.
* Lacock Abbey was used for some of the classrooms, including the Potions classroom and the Herbology greenhouse.
* Glenfinnan Viaduct was used for the famous shots of the Hogwarts Express train traveling over the bridge.
* Leadenhall Market in London was used for Diagon Alley.
So, while Alnwick Castle is the iconic landmark associated with Hogwarts, it was just one part of the many locations used to bring the magical world to life on screen.