The Pentagon is the headquarters of the US Department of Defense.
Tips
usage
In Chinese news, 五角大楼 is used as a metonym for the US military establishment, just as 'the Pentagon' is used in English. It often appears in geopolitical reporting.
memory
The Chinese name is a literal description of the building's shape: 五角 (five corners) + 大楼 (big building). Unlike the English name 'Pentagon' (from Greek), the Chinese is instantly transparent.