Farnham Castle is a 12th-century castle in Farnham, Surrey, England. It was formerly the residence of the Bishops of Winchester.

Farnham is a market town and civil parish in Surrey, England, around 36 miles (58 km) southwest of London. It is in the Borough of Waverley, close to the county border with Hampshire. The town is on the north branch of the River Wey, a tributary of the Thames, and is at the western end of the North Downs. The civil parish, which includes the villages of Badshot Lea, Hale and Wrecclesham, covers 14.1 sq mi (37 km2) and had a population of 39,488 in 2011.