Hi. Just wondering if somebody is working on any projects related to Urban Environment generation and if so would you like to discuss them? I am trying to figure out: How people are currently making 3D models of entire cities?

Cities are generally constructed using "modular" section of buildings that can be rearranged and combined into unique looking structures. It's like playing with lego: each building is different, but they're all using the same pieces. This not only saves you from having to model tons of unique buildings by hand but also helps file size & framerate since you're reusing the same pieces.