Arcology-Oddly prevalent with ponies, even with their small (by human standards) populations.  Mostly because it’s easier to preserve nature if you can concentrate ponies into one place, it’s easier to environmentally secure if needed, and ponies don’t go into a lot of material possessions.  Equestria itself has a huge number of arcologies, mostly because of the government’s goal to restore as much of the planet’s environments as possible.  Made very possible by modern technology, which makes most arcology blocks nearly self-sufficient.