You have a nice start on the geometry there.
The best way to get reference material for this is to play the movie on your PC and take some screenshots of the areas you are working on.
Take a look at Blushing Bride’s map “Cathedral”, It most resembles Hogwarts in design and texturing and parts of the movies were filmed at places where he got his inspiration from.
Back in 2004 I was working on a similar map - I had a initial layout of the great hall and entrance blocked out with a generic texture set in place (Socks Egyptian textures) so I could get the scale right. I had a fully functional map that I could run around in to test scripts, spawns, objectives, etc before I continued onto the rest of the level.
When the third movie came out (Prisoner of Azkaban) they did away with the front entrance stairs and went to the open courtyard that was used in the rest of the movies and I dropped the project because of time constraints.
I still have tons of screenshots and map backups stored somewhere if you’re looking for something in particular.
Here are a few exterior movie screenshots from the first two movies as well as a couple of progress pics of what I was working on.



I was going to resurrect this when Quake Wars came out and call it Stroggwarts, but I never got much past a basic terrain model and megatexture. :oppressor: