Attached Link: http://www.contentparadise.com/user/product.php?productid=12700&cat=1325&page=1

Perhaps you can save yourself some time and check out some of the cities that are ready to use? Follow the link and it will bring you to a free city. It's pretty big and easy to use. This isn't the only one, there are more free and not free cities around though. As for creating your own, xantor is correct. If I need a simple one (and the ready ones aren't suitable), I just use cubes in Poser. If I need a more detailed or complicated one, I design it TrueSpace and import it into Poser.

Artwork and 3DToons items, create the perfect place for you toon and other figures!

http://www.renderosity.com/mod/bcs/index.php?vendor=23722

Due to the childish TOS changes, I'm not allowed to link to my other products outside of Rendo anymore :(

Food for thought.....
https://www.youtube.com/watch?v=pYZw0dfLmLk