Raven Rock Mountain Complex, Cheyenne Mountain and the Greenbrier Bunker are underground bunkers in the United States. The Raven Rock Mountain Complex is located on the Pennsylvania-Maryland border. President Harry S. Truman approved its construction for emergency situations in 1950. It can accommodate up to 3,000 people.
Cheyenne Mountain Complex is in Colorado Springs, Colorado. It was built at the height of the Cold War as a command and control center and as a defense against Soviet aggression. It became a NORAD combat operations facility in 1967. The Greenbrier Bunker is located in West Virginia. The Washington Post exposed its location in 1992, ending its government use. It is open to the general public, as of 2015.