Executive Summary
The Raven Rock Mountain Complex, also known as “Site R”, is a highly secretive US military installation. Situated on the Pennsylvania-Maryland border, this strategically important facility lies nestled deep within Raven Rock Mountain. Conceived in 1950 by President Harry S. Truman, Site R was established as a secure relocation site for the Pentagon in the event of a national emergency, particularly a nuclear attack. Raven Rock is designed to ensure that government operations can continue even under the most extreme conditions.
This self-sufficient underground complex houses essential command and control functions, and communication hubs. It also houses life support systems capable of sustaining thousands of personnel underground for extended periods of time. Long shrouded in secrecy, its significance has been brought to light by events such as the September 11th attacks, reinforcing its continued role as a cornerstone of US national security and government planning.
Images Sourced From: The Black Vault, Public Intelligence,
1.0 Introduction
Deep within Raven Rock Mountain, near the presidential retreat Camp David, lies a top-secret facility. This US base is known by many names: Site R, Harry’s Hole, the Alternate Joint Communications Centre (AJCC), the Rock, and the “Underground Pentagon.” Over 70 years ago, constructors secretly blasted out masses of greenstone granite rock to create space for the sprawling complex. Hidden within the hollowed-out mountain stand clusters of three-story structures designed to resemble office buildings. [source, source]
Site R is entirely self-sufficient. It contains dual power plants to generate electricity, multiple underground water reservoirs, and a sophisticated ventilation system. Investigative journalist Eric Schlosser writes in his 2013 book, Command and Control: Nuclear Weapons, the Damascus Accident, and the Illusion of Safety, that the complex also offers a small chapel, and “enough beds to accommodate two thousand high-ranking officials from the Pentagon, the State Department, and the National Security Council.”
In the event of an emergency, the facility can support up to 3,000 government officials with its own power plant, water supply, and air filtration systems. It can also remain sealed off for months at a time. Access is limited, and only a select few with the highest security clearances and rigorous background checks may enter. Raven Rock stands as a testament to strategic foresight and the need for a resilient, alternative command centre during crises. [source, source, source]
2.0 History
2.1 Origins of the Raven Rock Mountain Complex
The genesis of the Raven Rock Mountain Complex traces back to 1950 when President Harry S. Truman approved its construction. This decision was a direct response to the escalating Cold War and the looming threat of a Soviet nuclear attack. Learning from World War II, during which Winston Churchill utilised an underground headquarters during the Blitz, American planners recognised the vulnerability of the Pentagon as an easily identifiable above-ground structure. The US government therefore designed Raven Rock to serve as an alternate command headquarters should such a catastrophe occur. [source]
Established during heightened Cold War tensions, Raven Rock has played a critical role in the United States’ emergency preparedness strategy. In 1956, plans for a nuclear attack included the creation of a Joint War Room Annex at Raven Rock, operated by the US Air Force. By 1958, officials integrated the facility into the broader North American Aerospace Defence Command (NORAD) Alert Network stations. Over time, Raven Rock underwent significant fortification to withstand nuclear blasts, similar to the Cheyenne Mountain complex. In 1976, Raven Rock aimed to expand its operational scope extensively. As a result, it opened the US Army Communications Command Site R Telecommunications Centre under the 7th Signal Command. [source]
2.2 Renewed Importance of Site R after 9/11
Although the Department of Defence considered closing Raven Rock in the years leading up to 9/11, the September 11th attacks reaffirmed its strategic value. Following the 9/11 attacks, authorities reportedly relocated Vice President Dick Cheney to Raven Rock as a secure, undisclosed location. This event demonstrated the facility’s role as a key component of the US government’s strategy to ensure leadership survival and continued operation during a major national emergency. Since then, the site has seen renewed attention. Visible signs of ongoing construction and upgrades suggest an expanded role in national security. [source, source, source]
2.3 Ongoing Operations and Modernisation
Raven Rock remains a fully operational military installation to this day, remaining central to the Continuity of Operations Plan (COOP) for the Office of the Secretary of Defence and the Joint Staff. It holds a minimum staff of approximately 100 members, with the capacity to house and protect thousands more. Moreover, it is home to a small number of missions and units. These include the Defence Threat Reduction Agency, the 114th Signal Battalion, and the Defence Information Systems Agency. [source]
The facility also serves as a major communications hub and has undergone significant modernisation in recent years. In August 2022, the Department of Defence awarded a $100 million contract to Grunley Construction, a Washington-based firm, for additional “design-bid-build” construction. This underscores the site’s continued strategic importance. [source]
2.4 The Secrecy and the Rumours: Separating Fact from Fiction
Raven Rock Mountain Complex is shrouded in secrecy, leading to numerous rumours and conspiracy theories about what lies within. While the general purpose and some basic features have become public knowledge, the specifics of day-to-day operations and the full extent of its capabilities remain highly classified. This intense secrecy was evident from its construction, initially disguised as a mining operation.
3.0 Organisation of Site R
3.1 Place within broader government and other structures
The Complex plays a critical role in supporting the Continuity of Operations Plan (COOP) for the Office of the Secretary of Defence and the Joint Chiefs of Staff. Designed as a secure backup to the Pentagon, Site-R houses emergency operation centres and provides relocation facilities for key components within the Department of Defence (DOD), as well as some other federal agencies. [source]
3.2 Site R Defence System
Raven Rock, or Site R, has a robust defence and security system. With its subterranean positioning within the granite Raven Rock Mountain walls, it is protected from nuclear blasts, electromagnetic pulses, and virtually all other catastrophic disasters. Engineers constructed the buildings within to stand separately from the granite cavern walls and sit independently on large springs, further enhancing resilience. Massive, reinforced blast doors and robust physical defences serve as major barrier protection in the event of emergency. [source]
Beyond its physical hardening, the site employs multi-layered security protocols to control access. Armed guards monitor the highly restricted entrance, and only authorised personnel that pass stringent clearances and biometric access controls can enter the facility. [source]
3.2 Communications Hub and Training Centre
Beyond its COOP mission, Raven Rock serves as a vital communications hub, supporting DOD users, DOD Nuclear Command Control and Communications (NC3) organisations, intelligence operations, and providing a national gateway for non-DOD users and U.S. allies. The facility’s highly advanced technologies ensure reliable communication with military and government entities worldwide, even during crises. These hardened systems can withstand electronic warfare and other forms of disruption. Site R functions as the Alternate National Military Command Centre (ANMCC) and also serves as an alternative command centre for both NORAD and USNORTHCOM, reinforcing its role in national defence and emergency readiness. As part of a broader continuity of government network, Raven Rock forms strong links with other US bases and bunkers, such as Cheyenne Mountain in Colorado and the Mount Weather Emergency Operations Centre in Virginia. [source, source]
3.3 Raven Rock Financing
The Complex received $45 million in government funding in 2018. Additionally, journalist Garrett Graff mentioned that the facility is funded annually with a $2 million federal budget. [source, source]
4.0 The Future of Raven Rock Mountain
The Raven Rock Mountain Complex continues to serve as a bastion of national security. According to the U.S. Army Corps of Engineers’ Forecast of Contracting Opportunities (March 2025), a project titled “Construct Fuel Storage and Access Road at Raven Rock Mountain Complex,” outlines plans to build enhanced fuel storage facilities. [source]
Although available information remains limited, these ongoing projects indicate a continued and growing importance for the facility in the future of national security and continuity of government planning. [source]
5.0 Conclusion
The Raven Rock Mountain Complex serves as a critical and highly secure installation. It ensures the continuity of essential government and military operations during national emergencies. From its secret Cold War origins to ongoing 21st-century upgrades, Raven Rock reflects a lasting investment in the nation’s leadership and survival in the face of extreme threats. Its self-sufficient infrastructure, advanced security measures, and strategic location near Washington D.C. and Camp David underscore its vital role as an underground citadel ready to safeguard the command and control functions of the United States. While there is limited data available surrounding its activities, the continuous modernisation efforts suggest its enduring importance in the evolving landscape of national security challenges.
