Castle Ring is a defended settlement, located on Harthill Moor near Birchover in Derbyshire.
The settlement is classed as a univallate hillfort, which lies in an area littered with prehistoric monuments, including a second defended settlement.
The Ring as a sub-circular enclosure with a defencive bank, an external ditch and counterscarp bank surrounding an area of approx 5,000m. The internal bank or rampart appears to be of simple dump construction in an oval hill-fort except to the S.E. where both banks and ditch have disappeared. This is where the entrance is thought to have been.
The monument has not been excavated and is a Scheduled monument.