Duffield Castle, Derbyshire
The rocky site was easy to defend, because it was surrounded by the river in three sides and hard to climb. It is not clear whether the site was inhabited in prehistoric times. The Roman army might have been there to protect the ford nearby where people from Lutudarum Wirksworth passed before joining Rykneld Street at Derventio (now part of Derby) which was N-shaped route for the North Sea ports.