It’s not free of course, but for $29 it’s hard to complain.
http://www.gamr7.com/init/default/index
I realize there is a Blender city generator, but it lacks a lot of the features that this software has. This is another share and pay promotion, similar to the PMG offer months back. It seems to run pretty well, although the generation process is a bit slow at times. The nodal workflow is pretty simple too.