I stumbled upon some web sites with photos of 3D sidewalk-art by English artist Julian Beever. Click here to see a larger image.
All of the images I have seen show the artist interacting with his work, which are amazing, three dimensional chalk drawings. The one shown on the right is one of my favorites, here Julian is teetering on the edge of a burning building while Batman and Robin come to save him.
You can see lots of other examples at Julian Beaver’s web site. Also here are some other web sites with photos of his work: