Fort Knox, Kentucky -
U.S. Bullion Depository

The United States Bullion Depository, commonly called Fort Knox, is a fortified vault building located adjacent to Fort Knox, Kentucky, which is used to store a large portion of United States official gold reserves and, occasionally, other precious items belonging or entrusted to the federal government.

The United States Bullion Depository holds about 4,603 tons (4,176 metric tonnes) of gold bullion (147.4 million troy ounces[1]). It is second in the United States only to the Federal Reserve Bank of New York's underground vault in Manhattan, which holds about 5,000 metric tonnes of gold in trust for many foreign nations, central banks and official international organizations. [Tom Hurt, 03/06/2010]

[RA: It's not open for tours, and travelers can't get close to the famous building. Someone should build a theme park with a replica! Everything we know about the interior comes from Goldfinger, which is probably as accurate as our knowledge of the inside of Air Force One.]