Insanely Secret Mountain Facility
The Cheyenne Mountain Complex isn't so secret for those who live in the area, but it was definitely not well-known among other people who live in the states. This facility only allows high-class officials to enter the premises. The classified photo shows a heavily armed guard at the entrance. Obviously, the CIA wasn't too keen on having such a forceful photo out in the open, which is why it wasn't released to the public for so many years.