Raven Rock: The Underground Pentagon Inside a Pennsylvania Mountain

In the early years of the Cold War, the Soviet Union tested its first atomic bomb, and military planners in Washington faced a frightening question: if a nuclear attack destroyed the Pentagon, where would the military command the country's response? Their answer was a mountain in south-central Pennsylvania, a few miles north of the Maryland line. On January 23, 1951, the federal government filed a legal taking of the land at the Adams County courthouse. That same month, crews and machinery converged on the mountain. They blasted into dense greenstone rock, driving tunnels about half a mile into the mountain. The tunnels were gently curved, reportedly to lessen the effects of a blast. A 1951 news report described plans for an underground chamber 2,100 feet long, with room for a staff of 1,200 in peacetime and 5,000 in wartime. The work was hard and dangerous. There were accidental deaths on the site in 1951, and in March 1952, more than 100 workers went on strike over related construction at nearby Camp Ritchie. The initial phase cost about $35 million. In 1953, the facility became operational as the Alternate Joint Communications Center, Site R, with "R" standing for Raven Rock. Inside the mountain, the complex grew over the following decades. According to Cold War communications historians, the interior holds five three-story buildings, labeled A through E. Other accounts describe the buildings mounted on spring systems and the tunnels sealed by 30-ton blast doors. In 1955, the Office of the Secretary of Defense approved automatic activation of Raven Rock's communications center upon notice of a nuclear attack. The nickname "the Underground Pentagon" stuck, along with others: "the Rock," "the Backup Pentagon," and the National Military Command Center Reservation. The complex runs 38 communications systems and holds emergency operations centers for the Army, Navy and Air Force. Raven Rock was never needed for the war it was built for. But unlike many Cold War bunkers, it was never closed either. It's still an active military installation, and from the roads around Blue Ridge Summit, all you can see of it is the wooded mountain and the towers on top.