in January 1954 the CIA, conceived a top-secret plan to tap telephone lines leading to and from the Russian embassy in Berlin. It would be a joint CIA and British SIS operation. The site selected was in a rural location close to a grave yard in the Rudow district of Berlin’s American sector and adjacent to the district of Altglienicke in the Soviet sector. Work began immediately to dig a tunnel close too and at right angles to the border, this would provide access to cables which were situated underground alongside a roadway which ran parallel to the border. The tunnel was approximately 430 meters long, two thirds of its’ length within the Soviet sector, and an internal diameter of two metres. At the outer end of the tunnel an equipment room was installed with amplifiers and repeater units. To disguise unusual digging activity from Russian observers, an externally unremarkable warehouse building with a very deep basement was constructed, from which the tunnel was excavated horizontally. By May 1955 the tunnel was completed and the Russian cables containing an estimated 1200 telephone lines were tapped. It was a mother-lode of information that kept 650 translators and analysts based in Washington and London busy around the clock for the next year. It was not to last. In the spring of 1956 heavy rains inundated Berlin saturating the earth and interrupting the service of a number of cables. In the early morning hours of April 22, 1956 the American spies watching from their disguised location were horrified to see a team of German workers digging directly above their tunnel. Within hours the tap was discovered and the listening devices shut down.