What is the best practice for moddeling complex structures? Using a single mesh, multiple meshes or multiple objects? 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.
You can make things as separate objects, if you'd like. When you do so, use parenting.
You can still do it as one mesh, its up to you how you want to go about things. Eventually, you'll use bones and you'll need to use parenting then.
https://www.youtube.com/watch?v=o5f18T7Rjmc
https://www.youtube.com/watch?time_continue=73&amp;v=GS452KMVWKA&amp;feature=emb_logo