"Sullivan uses his observations on vermin to examine New York's urban history. He also believes rats mirror humans. "I observe these rats, and they come out of their hole, they go to the same place each day to feed and then they go back to their hole for bed," he says. "Then I turn around and look at Wall Street, and I see all of these people coming out of holes in the ground, going to breakfast, going into their buildings and then going home."