Cheyenne Mountain Complex

The Cheyenne Mountain Complex is a military installation built deep inside a granite mountain near Colorado Springs, Colorado. Excavated in the 1960s at the height of the Cold War, it houses a network of buildings mounted on giant springs behind blast doors, designed to survive a nuclear strike. For decades it was the command center for NORAD's missile-warning and air-defense mission — today it serves as an alternate command site and remains an active, restricted facility.

• Colorado
  The highest state, crown of the Rocky Mountains related