In 1935, portions of property in the Fort Knox military reservation were set aside for use as the U.S. Bullion Depository. Constructed in 1936, it was placed under the supervision of the Director of the Mint, a U.S. Treasury official. The first gold was brought here by railroad in 1937, and the depository continues to be the storage site for most of the nation's gold. By law, it is not open to public visits or tours.