Idiom idiom
Fort Knox
Meaning
A place which is very difficult to get into.
Meaning adapted from Wiktionary, available under CC BY-SA 4.0.
Examples
“My brother keeps his room like Fort Knox.”
“The company security is like Fort Knox, so you need a special badge to enter the building.”
“With its biometric scanners and armed guards, the private research facility was effectively a modern-day Fort Knox, impenetrable to any unauthorized visitor.”
Origin
Named after Henry Knox, who served as the Continental Army's chief of artillery during the American Revolution and later as the first United States Secretary of War.
Anchors to
Last updated August 10, 2026