*fm a previous thread repy by BecSchm

"...If you can use flat-topped houses, make a terrain (the default one will work), then while holding down the ALT key, roll your mouse over the POSTERIZE marble until you get a grid pattern that you like.  Render away! ..."*

I might add that if you 1) create a terrain 2) duplicate it 3) inside terrain editor, posterize it as becschm described 4) release the mouse button and do it a second time it will create varying shaped rectangular maps.  Experiment with amount of posterization. Back in the scene, lower the posterized terrain a bit and raise its height so the greeble extends out of the original terrain.  Tah dah!  Miscellaneous shape buildings with spacing like streets.