A

**square mile**(symbol

**mi²**) is an imperial unit which is the area of a square whose side is one mile (or 5,280 feet). A square mile is equal to 27,878,400 square feet, 640 acres, or roughly 2½ square kilometers (2.589988 km², to be more exact).

*See also*: Conversion of units

In England,

**the Square Mile**is a traditional name for the City of London.