The fort is on a narrow east-west ridge reaching a height of 210 m, with steep natural slopes to the south and west, and linear ramparts facing north and east.
The fort was built by the Second Legion under Vespasian, during their conquest of the Durotriges and occupation of Dorset. It is possible that the fort originated as a temporary camp during the campaign against nearby Pilsdon Pen, where two Roman ballista bolts have been found.
First recognition of the site came when 19th century quarrying uncovered military artefacts from the 1st century AD. The site was investigated by Graham Webster in a series of archaeological excavations starting in 1959, which revealed the full layout of the camp, except for some small areas destroyed by the quarrying. The permanent structure of the fort appears to have been built and occupied in the period 50-60 AD, following the abandonment of Hod Hill further east. The Roman road to Waddon seems to have left the main Dorchester-Axminster road at Two Gates, passed through Eggardon Hill, then south of Beaminster, to enter Waddon from the east.