Banksy began his career by taking up wall space without permission for his street art. But his work has become so financially successful that established art institutions, ironically enough, have scrambled to become part of the Banksy mythology regardless of the artist's consent. Following the recent, controversial "Stealing Banksy" show, where Banksy's street art pieces mysterious appeared in a gallery setting, carved from the walls on which they originally appeared, London auction house and gallery Sotheby's is slated to open "Banksy: The Unauthorized Retrospective" on June 11.