Douglas Castle was a stronghold of the Douglas family from medieval times to the 20th century. The first castle, erected in the 13th century, was destroyed and replaced several times until the 18th century when a large mansion house was built in its place. This too was demolished in 1938, and today only a single corner tower of the 17th-century castle remains. The castle was the former family seat of the Prime Minister, Alec Douglas-Home. The castle was located around north-east of the village of Douglas, South Lanarkshire, in south-west Scotland. The remains are protected as a category C listed building.