 Peveril Castle in Castleton is roughly triangular in shape , about 90 by 65 m ( 295 by 213 ft ) , on top of a hill overlooking the Hope Valley . The land slopes steeply away from the castle 's perimeter , forming an almost sheer face to the south east , and the winding approach from the north is the most practical way to the castle . Not only was the site naturally defensible , but its prominence would have allowed the castle to be a highly visible symbol of the builder 's power . The town of Castleton provided supplies to the castle . It commands views of Hope Valley below and Treak Cliff , Mam Tor , Black Tor , and Lose Hill . The castle was entered through the gatehouse to the east . Its design was simple , 7 m ( 23 ft ) wide with a gatepassage 2 @.@ 5 m ( 8 ft 2 in ) across . Little survives , although earlier drawings contain details of mouldings that suggest the structure was built in the 12th century , perhaps by Henry II or King John . 
