I remember seeing a documentary on HBO called ‘naked states’ on works of Spencer Tunick, a couple of years ago. I don’t know how he does it, but he convinces hundreds and thousands of people to pose nude in public, arranges them in artistic and sometimes, bizzare formations (he calls them installations) and photographs them.

He started taking these photos in 1992 in New York and was arrested in 1994 for photographing a nude woman at Rockefeller Center in NYC. His largest installations consisted of 7000 spaniards in Barcelona and 1700 english men and women in London. Many of these pictures are quite fascinating and very surreal. Check them out at these links.