This one is remarkable for what it no longer does. A circular univallate enclosure, meaning a single-ditched or single-banked ring enclosure of the kind that dots the Irish countryside in various states of preservation, once occupied a position near the foot of the north-eastern end of Sea Hill ridge on the Dingle Peninsula, with Minard Head visible to the south-east. By the time anyone thought to record it carefully, it had already gone. It appears on the first edition of the Ordnance Survey map, drawn up in the nineteenth century, but has since vanished from the ground entirely, leaving only its cartographic ghost.

The site sits, or rather sat, in a landscape that repays attention even in the absence of the monument itself. Roughly seventy-five metres to the south lies Lissakilleen, a related enclosure that does survive, and the proximity of the two suggests this part of the ridge was once a more densely occupied or organised stretch of ground than it appears today. The Dingle Peninsula is unusually rich in early medieval and prehistoric remains, and the enclosure at Na Dúnta Thoir was recorded as part of J. Cuppage's 1986 archaeological survey of Corca Dhuibhne, a landmark regional study that catalogued monuments across the peninsula at a time when several were already under threat or in decline. The enclosure's disappearance between the first Ordnance Survey and the late twentieth century is not unusual; field clearance, agricultural improvement, and simple erosion have erased countless such features across Ireland, and the map record is often all that confirms they ever existed.