This model of Hogwarts was used in all the exterior shots in the movies. You can read an article about it here and also see the true size of the model.
This is the last post I'll publish with photos from the Warner Brothers Studio Tour - the Making of Harry Potter. I have so many more photos from this magical place, but I think you'd get tired of me if I keep posting about it, haha. I recommend every Harry Potter fan to make a visit here, if you ever go to London :)