Fort Knox

== English == === Etymology === Named after Henry Knox, the Continental Army's chief of artillery during the American Revolution and the first United States Secretary of War. === Proper noun === Fort Knox A United States Army base located in Kentucky, United States. The United States Bullion Depository, a vault where gold reserves are stored. === Noun === Fort Knox (idiomatic) A place which is very difficult to get into. === Usage notes === The proper noun is commonly used in similes; for example, as safe as Fort Knox.