This is the original home of the US's nuclear arsenal and its been a top secret for over 60 years. The place was built in 1948 and 1949 and the Tunnel Vault was one of the most highly secured facilities in the US.

It reaches 230 feet into a canyon wall and behind a bank vault door, there are five storage bunkers each with its own vault door inside a larger vault. Talk about super secure.

The vault was buried some 300 feet underground, and it was the storage site for the US's first nuclear weapons developed at the nearby Los Alamos National Laboratory under the Manhattan Project.

To commemorate the 70th anniversary of the Los Alamos National Laboratory, the vault was opened this week to tours for media, employees and their families. Check out the video below:

[Los Alamos National Lab via PhysOrg]