FORT KNOX
Arguably the most secure building on the U.S. mainland, Fort Knox and its various security measures are shrouded in mystery. What is known about the building is that the front door is only accessed by Depository staff at random schedules. The staff must each enter a different combination code to unlock the door and the code changes daily. Because the facility secures an estimated $270 billion in gold and treasures, traditional lock and keys are not utilized as far as the public is aware.