Down a remote canyon near Los Alamos National Laboratory lies a facility known as the “Tunnel Vault,” once one of the most secret and secure locations in the United States, it’s the original post-WWII nuclear stockpile storage area.
Located in Los Alamos canyon at Technical Area 41, the Tunnel Vault was built between 1948 and 1949. The facility has a formidable security perimeter, a hardened guard tower — complete with gun ports and bulletproof glass — and a series of gates and doors that lead to a 230-foot long concrete tunnel that goes straight into the canyon wall.
At the end of the tunnel is a large alcove room with a single bank vault door. Through that door is a vault built inside a vault with five storage areas, all protected with identical bank vault doors.
Check out the video that tours the declassified facility available on the Los Alamos National Laboratory YouTube.