Everything Everywhere Daily · Sunday, September 13, 2026
The Cheyenne Mountain complex is protected by two giant steel blast doors, weighing an estimated 20 to 25 tons each and about three and a half feet thick. These doors are carefully balanced to close in approximately 45 seconds and are only shut during actual crises or training exercises to prevent pressure differences from holding them shut. The tunnel geometry leading to the complex is also designed to dissipate blast wave energy.
“The most famous piece of Cheyenne Mountain engineering are its enormous blast doors.”
“Two giant steel blast doors conceal the entire complex from the outside. Estimates vary slightly depending on the particular door and period, but they weigh roughly 20 to 25 tons each and are about a meter, or about three and a half feet thick.”
“Despite their enormous mass, the doors are balanced so carefully that they can be shut in just 45 seconds.”