This is a model generated with the software City Engine. This brilliant little gem has saved me weeks of hard labour at a computer screen. It is a procedural model generator. It does pretty much the same things as the procedural brushes in Maya, but it is focussed on generating urban models. Procedural means that the terrain and building geometry are generated mathematically. CE has parameters for social status and wealth as well as geographical parameters. You can control the distribution of buildings by painting reference maps that tell the software where the wealth is concentrated in the town. Height is controlled by the same method.
My model is generated from the medieval sample. I am using it as the backdrop that will be seen through the widows of the room where the Patrick Stewart portrait is going to be set. The quality is OK from a distance. The rooves and buildings are fine for my purposes but the ground and trees will be replaced.