This guy is incredible. From Rense:
Julian Beever is an English artist who is famous for his art on the pavements of England, France, Germany, USA, Australia and Belgium. Its peculiarity? Beever gives his drawings an anamorphosis view, his images are drawn in such a way which gives them three dimensionality when viewing from the correct angle.
Here is an image from the incorrect angle:
Here it is again from the correct angle:
(via the Kircher Society)