What was once a cashel, a type of ringfort built from drystone rather than earthen banks, has been partially swallowed by a later field wall that runs along its northern to eastern arc. The two phases of construction have merged to the point where it takes some attention to separate early medieval intention from generations of agricultural convenience.

The cashel measures approximately 41 metres north to south and 38 metres east to west, making it a substantial enclosure of the kind that would once have sheltered a farming household and their livestock within its stone circuit. Cashels of this type are generally associated with the early medieval period in Ireland, roughly the fifth to twelfth centuries, and were the dominant settlement form across much of the west of the country where stone was more readily available than the material needed for earthen raths. At Bunatober, the defining wall is poorly preserved for much of its circuit, but a gap at the north-west has been noted as a possible original entrance, which would give some sense of how the enclosure was once oriented and used.