Cadbury Hill is a small multivallate hillfort situated on a natural and commanding ridge which separates the Gordano Valley from the Somerset Levels.
The hillfort is well preserved and has a sub-circular interior 190m north-south by 160m east-west, surrounded by a double set of ramparts c.26.5m across. The internal ditch is circa 2m deep and the internal bank is circa 2m high; together these earthworks are circa 18m wide. The external rampart is circa 1.5m high and the ditch is circa 2m deep; the joint width of these earthworks is circa 8.5m.
The banks are constructed of small stones, quarried from the ditches. The hillfort has three entrances, though only the northern entrance is thought to be original.
Excavations on the hillfort were carried out by St George Gray in 1922 and he uncovered Iron Age and Romano-British artefacts from the interior. Other finds from the hillfort include: Neolithic flints, a Bronze Age axe, late Roman coin hoards, a quern stone, a brass of Claudius Gothicus and part of a possible Roman altar of Mars. This Romano-British relief (now in North Somerset Musuem) may be a local version of a Roman god, possibly Mars or Silvanus.
During the Second World War a searchlight battery was established on the hillfort and the site was also used for bomb disposal.