Harrow is a town in Greater London, England, and serves as the principal settlement of the London Borough of Harrow. The eastern part of the town, by Northwick Park Hospital, crosses the London Borough of Brent border. Harrow lies about 9.5 miles (15.3 km) north-west of Charing Cross and 5.4 miles (8.7 km) south of Watford. In 2022, the town and localities had an estimated population of 117,651, whereas the wider borough had a population of 261,185.