Fort Knox vaults

The Fort Knox vaults, home to most U.S. gold reserves, have been deemed the most heavily guarded place on the planet. Besides gold, Fort Knox has also held, among other things, the US Constitution, part of the Hungarian Crown Jewels, and reserves of morphine and opium. No single person can make it into the vault. Several combinations need to be entered to gain access, and various staff members know just one. Even they wouldn’t be able to get in without the help of their colleagues.