Robert A. Caro's The Power Broker has been called "the greatest book every written about a city." This groundbreaking work revealed how Robert Moses -- a man never elected to public office -- spent decades amassing power so immense that he was able to reshape New York City. Now, a new exhibit at the New York Historical Society, Turn Every Page: Inside the Robert A. Caro Archive, explores the story behind the book and the meticulous, methodical research Robert Caro conducted to write it. Valerie Paley, New York Historical Society senior vice president, discusses the show on view now.