The fort and fortlet at Castleshaw are situated on a step of Grindslow shale on the eastern side of Castleshaw Valley below Standedge, part of the Pennine ridge in northern England. From the site there are clear views up and down the valley, although it is overshadowed by higher ground on all sides. It is remote and exposed and lies along the Deva Victrix (Chester) to Eboracum (York) Roman road. The road crosses the Pennines at Standedge where the area dips and narrows, creating a traversable pass which would have been guarded by the Castleshaw fort. The nearest forts are Mamucium (Manchester) to the west and one at Slack to the east, both on the line of the Roman road. There was also possibly a fortlet or signal station at Worlow, between Slack and Castleshaw. The later fortlet is on the same site as the fort (grid reference ).