If you're building romanesque churches, castles, those kinds of builds... if you want it to look more accurate, keep in mind that part of the reason for the architecture they had was structural. They couldn't build up like we can today without supporting it heavily. Tall buildings usually had a ton of adjoining rooms and supports and such, up until good steel came about in the 1880s and 1890s... even then the first few skyscrapers weren't just plain boxes. Google the Hagia Sofia, that's a good example - without every single one of those little domes and adjoining rooms, that big dome in the middle couldn't exist (even then, actually, it's apparently collapsed like three times or something.)
So that's the other way to prevent having big plain walls! :D
A little impractical for this build since you're so far in, but I think it's important to bear in mind.
(what I get from studying architecture...)
