a military building in the US state of Kentucky which holds the government's store of gold. People often use the name 'Fort Knox' when talking about a place that is extremely well guarded or impossible to enter without permission. U.S. military reservation, northern Kentucky, U.S., southwest of Louisville. Occupying an area of 110,000 acres (44,510 hectares), it was established in 1918 as Camp Knox and became a permanent military post in 1932. The U.S. Gold Bullion Depository, a bombproof structure protected by elaborate security devices, was built there in 1936 to hold the bulk of the country's gold. Since 1940 it has been the U.S. Army Armor Headquarters and the site of associated training schools