ahhhh cool!!!!! i WISH i had a program that i could do awesome city design in.... i need something with easy graphics tools like and architect program but not tricky CAD stuff (well its time consuming), mixed with the ability to do huge detailed cities like this, but also go inside and design some of the buildings. I can't imagine the processor power needed... I know there are are few programs that i could try but they are totally ground up stuff . so a mix of CAD, the sims, house design software and decorations.. lol
But i do love city build stuff
Probably try Blender. It's free and has a bit of everything.