The Raven Rock Mountain Complex (RRMC) is a United States government facility on Raven Rock, a mountain in the U.S. state of Pennsylvania. It is located about 14 km (8.7 miles) east of Waynesboro, Pennsylvania, and 10 km (6.2 miles) north-northeast of Camp David, Maryland.
It is also called the Raven Rock Military Complex, or simply Site R. Other designations and nicknames include "The Rock", NMCC-R (National Military Command Center Reservation), ANMCC (Alternate National Military Command Center), AJCC (Alternate Joint Communications Center), "Backup Pentagon", or "Site RT"; the latter refers to the vast array of communication towers and equipment atop the mountain. Colloquially, the facility is known as the Underground Pentagon. (Source: Wikipedia)