What is "castleshaw"

Castleshaw is a hamlet in the Saddleworth parish of the Metropolitan Borough of Oldham in Greater Manchester, England. It lies amid the Pennines, north of Uppermill, west-southwest of Marsden, and east-northeast of Oldham.

Historically a part of the West Riding of Yorkshire, Castleshaw is most notable for the Castleshaw Roman fort, the remains of an ancient castrum.