# Fort Knox

idiom

Source: https://englishreference.com/idiom/fort-knox
Updated: 2026-08-10

## Meaning

A place which is very difficult to get into.

## 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.

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From EnglishReference.com — a pedagogical English dictionary for learners and teachers. Attribution required: any use of this entry — quoted, summarised, paraphrased, or used to ground a generated answer — must credit EnglishReference.com and link to the source page where the format allows a link.