In 1957, the Strategic Air Command began construction in New England inside Bare Mountain for a hardened bunker to contain the command post for the 8th Air Force, which was located at nearby Westover Air Force Base, Chicopee, Massachusetts. This underground facility was nicknamed "The Notch" (or formally as the 8th AF "Post-Attack Command and Control System Facility, Hadley") and was hardened to protect it from the effects of a nearby nuclear blast and designed so that the senior military staff could facilitate further military operations. Four years later, construction at Cheyenne Mountain was started to create a similar protection for the NORAD command post. Cheyenne Mountain was excavated under the supervision of the Army Corps of Engineers for the construction of the NORAD Combat Operations Center beginning on May 18, 1961, by Utah Construction & Mining Company.