Doncaster is a city in South Yorkshire, England. Named after the River Don, it is the administrative centre of the City of Doncaster metropolitan borough, and is the second largest settlement in South Yorkshire after Sheffield. Noted for its racing and railway history, it is situated in the Don Valley on the western edge of the Humberhead Levels and east of the Pennines. It had a population of 87,455 at the 2021 census, whilst its built-up area had a population of 160,220, and the wider metropolitan borough had a population of 308,100.