The Cheyenne Mountain bunker in Colorado Springs, which was the filming location for the popular Stargate SG-1 science fiction TV series, was first built in 1965 to resist a Soviet nuclear attack. It was a key center for United States Space Command and North American Aerospace Defense Command (NORAD), which scanned Canadian and US airspace via a worldwide system of missiles.
The site was abandoned in 2006 due to heavy costs, and since then the complex has been merely on "warm standby," meaning it is only staffed when required .... http://rt.com/usa