Shortly before Rudy Giuliani left the New York mayor's office in 2001, close associates worked out an unprecedented and controversial deal to transfer his mayoral papers from city hall to a private, tax-exempt foundation, the Rudolph W. Giuliani Center for Urban Affairs. Billed as a leadership think tank, the center served as a conduit for Giuliani to copy and archive 2,100 boxes of documents from his time as mayor before returning the originals to the city. That record, which includes the months after the Sept. 11 attacks when he was anointed as "America's mayor," serves as the foundation of Giuliani's...