I'd like to share with you a set of print-out art created by Made by Joel. This site is one of my favorite site for original children art. This collection is from his Paper City Collection. Simply click to enlarge the following images and get your city running!
Another site that I would like to recommend for print-out art is called Cubecraft. Simply download, print, cut and fold - you can add some 3D cube-head people to your paper city! How fun!