Raven Rock Mountain Complex (Site R)

Hidden beneath the mountains along the Pennsylvania–Maryland border, Raven Rock Mountain Complex—known as Site R—is one of the United States’ most secure and strategically important facilities. Built during the Cold War, it serves as a hardened underground command center designed to ensure continuity of operations in the most extreme scenarios.

Often referred to as the “underground Pentagon,” Site R supports critical defense coordination and communications, operating out of a fortified network carved deep into the mountain. Its existence reflects a legacy of preparedness, resilience, and quiet strength.

A symbol of unseen infrastructure and enduring readiness—Raven Rock remains largely out of sight, but never out of mission.