The best 3D street drawing I have seen. It is admirable how the painter blended himself and a wall in the side-walk into the drawing. Note that it is done on a flat surface. Very neat. You can view more of his street arts here:
http://users.skynet.be/J.Beever/pave.htm
I am wondering about the science behind this. Like more details on how exactly the artist gives 3D perceptions on a flat surface. I would really be interested in learning this one day. :-)