Set into an east-facing slope amid undulating pasture at Ballymartin, this ringfort is a roughly circular earthwork measuring around 31 metres north to south and 33 metres east to west, defined by a low earthen bank that still stands about half a metre high. Its most considered feature is the entrance on the eastern side: a ramp roughly six metres long and one and a half metres wide, flanked on either side by linear earthen banks, as though whoever built this place wanted to manage not just access but the impression of arrival.

Ringforts, known in Irish as raths when constructed from earth rather than stone, were the standard form of enclosed farmstead in early medieval Ireland, typically dating from roughly the fifth to the twelfth centuries. Most were home to a single farming family, the enclosing bank offering a degree of security for livestock as much as for people. What distinguishes this example is what lies inside: four low stone mounds are distributed across the interior, the purpose of which is not entirely clear, though such features can represent the footings of former structures, storage areas, or later disturbance. A gap on the west-northwest side of the bank may be an original secondary opening or simply a point of deterioration over the centuries. A second ringfort sits roughly 150 metres to the north, suggesting that this part of Ballymartin supported a cluster of early settlement activity rather than a single isolated farmstead. The site was recorded in a 1994 archaeological survey of the Ballinrobe district compiled by D. Lavelle for the Lough Mask and Lough Carra Tourist Development Association.