Construction of NORAD Air Defense Command
North American Air Defense Command underground Combat Operations Center is a Nuclear War hardened installation near Colorado Springs, Colorado. The installation takes up about 5 acres, tunneled into part of the Cheyenne Mountain massif, and was designed for a 30 megaton nuclear explosion within 1.2 mile radius. The excavation work for the construction started in 1962, and full operational capability was achieved in July, 1966.