Holwell Castle, at Parracombe, was a Norman motte-and-bailey castle built to guard the junction of the east–west and north–south trade routes, enabling movement of people and goods and the growth of the population. Alternative explanations for its construction suggest it may have been constructed to obtain taxes at the River Heddon bridging place, or to protect and supervise silver mining in the area around Combe Martin. It was in diameter and high above the bottom of a rock cut ditch which is deep. It was built, in the late 11th or early 12th century. The earthworks of the castle are still clearly visible from a nearby footpath, but there is no public access to them.