Someone did something like this before. It was one of Escher's peices. If I remember right, they modeled all of it but one tiny part (in the image from the link, one of the step sections just to the left of the top right-most tower), so when the camera was in the right spot, creating the effect in the peice. Its impossible (I think atleast) to actually model it out the way it looks. Ill see if I can find out who did it, so you guys know what Im talking about.