This isn't just one device, it's a whole tunnel full of spy tools. Soviet authorities discovered amplifiers and other gizmos used to tap Russian telephone lines inside this long tunnel in Berlin, Germany, during the Cold War. Russian officials broke into its eastern end on April 21, 1956, and announced the tunnel's existence on April 23, accusing American authorities of digging it from their Berlin sector across the border line. The tunnel's discovery sparked a major propaganda campaign against the West, with about 50,000 East German citizens bused in to see it. Built in 1955 and code-named "Stopwatch" by the British and "Gold" by the Americans, the $6.7 million construction was operated jointly by the CIA and the British SIS. It ran from Rudow in West Berlin to Alt-Glienicke in East Berlin, which was occupied by the Soviets. Unfortunately, while it was still on the drawing boards, the tunnel project was leaked to the Soviet KGB by British double agent George Blake. Still, during its brief existence in operation — 11 months and 11 days — American and British intelligence recorded 440,000 phone calls regarding Red Army maneuvers in East Germany.