A city planed and build with a friend, the problem was our ambition, we wanted to build a 2000x2000 city by hand with no pluging, and that proven to be way too huge for two student.
We had to use a 3rd party software to create the 2000x2000 flat map, because that functionality was not in the game at the time (creative mod was not implemented too), and that created a lot of performance issue and we really struggled to have the map on a server correctly.
I'm still surprised that we made all interior and to this day, sometimes I discover some place under some building, like the pyramid under the Wooden House I discovered on sketchfab
This building was planed for the town. The plan of it and itss neighborhood is bellow.