7. Cheyenne Mountain, Colorado, USA
Media Source: mentalfloss.com
The Employees at the Cheyenne Mountain Complex work behind 25-ton doors who are fully resistant to a 30-megaton blast. To calculate that, If you want to blast the door you would need the Fat Man – the bomb dropped on Nagasaki to explode 1429 times. The offices are 2000 feet below the mountain’s granite, far enough so air has to be pumped inside. However, in case of an Armageddon, I am definitely booking a ticket to fly to there!