Romans were the first to invent Mile. In Latin mille means one thousand.

A mille passuum was one thousand paces or one mile.

So when each pace is equal to two steps or 5 feet, one mile = 5000feet.

Furlong was the more conventional unit of length.

So a mile was rounded off to 5280 feet so that

1 mile = 8 furlongs = 1760 yards = 5280 feet.

The new length was fixed by an act of Parliament in the 16th Century.