I want to make a model that is big enough to have characters walk around and inside of it. I already have it roughed out (see picture), but now that I want to add detail (windows, railings, pipes...) I was wondering what the best way to do this is: keep the entire thing as a single mesh, make the details as separate meshes in the same object, or make them different objects altogether? What sections are the best to separate out?
Related to that: how do I keep everything together when the big thing is animated?
Model of the big thing. The total height is 20m. Around the 3d cursor is a human rig for scale.