Children play at the Ryoji Ikeda exhibition “the transfinite” at the Park Avenue Armory on June 10, 2011 in New York City. The audio visual installation, which will close after tomorrow, features two back-two-back screens displaying a continual loop of sounds, fragments of numbers and strobe-lit patterns that echo the Japanese artist's interest in mathematics, the subconscious and the digital world. (Photo by Spencer Platt/Getty Images)

A man takes a picture of part of what is set to be the UK's largest street art project on August 19, 2011 in Bristol, England. The See No Evil art project on Nelson Street in Bristol will see several multi story buildings in the street covered with art over the coming days. Organisers hope that the project, which has involved top graffiti artists from all over the world, will become a major tourist attraction for the west country city, often said to the spiritual home of Banksy. (Photo by Matt Cardy/Getty Images)