It has long been public knowledge that Cheyenne Mountain is the home of NORAD, a joint American/Canadian organization devoted to maintaining the security of North American airspace. Its historic task was as watchman for the threat of nuclear attack from the Soviet Union. Unbeknownst to the public, however, Cheyenne Mountain has for the past decade also been home to Stargate Command.
Cheyenne Mountain contains nearly a skyscraper's worth of floors, but with one significant difference to a skyscraper; instead of going 20 or more floors up, it instead descends an unknown number of levels under the mountain. While the full extent of the facilities available to personnel within Cheyenne Mountain is unknown, it is at least certain that the complex sports several cafeterias and troop's barracks, at least one gym, a fully equipped infirmary, and several multi-purpose observation rooms, which are used for such things as complex surgery, interrogation, imprisonment, and volatile scientific experiments.
Cheyenne Mountain also appears to include several old missile silos, one of which now houses the Stargate. It is through the surface opening of the gateroom silo that the Stargate was originally moved into the facility sometime prior to the first mission to Abydos.
- In an alternate reality that Daniel Jackson visited in February 1998, Cheyenne Mountain was the headquarters of the SGA, which was a program headed by Catherine Langford that discovered how to activate the Stargate. However, they made an enemy of the Goa'uld. Four days before Daniel's arrival in this reality, Apophis had begun to systematically wipe out the Earth, resulting in the destruction of many cities and putting the death at one point five billion people. Arguably futile efforts to combat him were headed through the mountain, which Apophis's forces eventually invaded. As many people as possible tried to escape through the Stargate to the Beta Site before his forces captured the entire mountain. To prevent the facility from failing to Apophis' hands, Colonel George Hammond ordered Dr. Samantha Carter to set the mountain on auto-destruct. Just as Teal'c, the First Prime of Apophis, reached the gate room and the Daniel of our reality escaped back through the Stargate, the self-destruct hit zero and the mountain blew up, destroying it while also killing the Jaffa troops invading the SGA. (SG1: "There But for the Grace of God")
- In another alternate reality, Cheyenne Mountain was invaded by Apophis' forces led by Teal'c in 1999. It was retaken with the help of the Asgard after they were contacted by Dr. Samantha Carter. (SG1: "Point of View")
- In another alternate reality visited by Samantha Carter in 2007, Cheyenne Mountain was used by President Henry Landry as his base of operations, with the General's Office serving as the Oval Office. (SG1: "The Road Not Taken")
- In an alternate timeline accidentally created by SG-1 in which Stargate Command never existed, Cheyenne Mountain housed the USAF Research Institute in 2005. It was under the command of Brigadier General George Hammond. After the Beta Gate was discovered in Antarctica by Daniel Jackson and Samantha Carter, it was installed in the facility. (SG1: "Moebius, Part 1", "Moebius, Part 2")