Suicidator City Generator (SCG) is a popular Python script for Blender. With it, you can automatically create entire, three-dimensional modern cities in a matter of seconds by adjusting various parameters, such as city size and complexity, rather than creating each building, each street, and each texture manually. City-builder add-on Suicidator has been updated to version 0.5, which is able for Blender 2.6. This version so contains automatic building and street generator and also building texture generator and terrain elevation control.
While a free version is still available, you’ll have to pay for more complex city models.
For more details visit: Suicidator City Engine