borough (district), administrative and historic county of Surrey, England, at the foot of the North Downs, on the southwestern periphery of Greater London. It became important with the discovery (c. 1618) of mineral springs (from which Epsom salts were named). Horse racing began there as early as the residence of James I (1603–1625) at Nonsuch Park, becoming permanent in 1730. The famous Epsom meeting, at which the main races are the Derby (1780) and the Oaks (1779), takes place in the first week of June. Many racing stables also use the chalk downs. The town of Epsom is now the shopping centre of a large suburban area. Area 13 square miles (34 square km). Pop. (2001) 64,493.