"Through every era of American history, Philadelphia has been a battleground for espionage, where secrets are created, stolen, and passed through clandestine meetings and covert communications. Some spies do their work and escape, while others are compromised, imprisoned, and--a few--executed. "Spy Sites of Philadelphia" takes you inside this shadowy world and reveals the places where it all happened. In 131 main entries as well as listings for dozens...