On the eastern bank, a small triangular spit of land juts out, barely twenty-nine by thirty metres in extent, with sheer drops to the north and south and only a narrow earthen barrier closing off its landward side. That barrier, an earthen bank averaging four metres wide at the base and standing two metres high on its outer face, is the defining feature of what locals have long called An Dún, the fort. Promontory forts of this type use natural coastal geography to do most of the defensive work, requiring only a single rampart across the neck of land that connects the headland to the mainland. Here, nature has been unusually generous, leaving the builders very little to do.

The site was recorded in detail by J. Cuppage as part of the 1986 Corca Dhuibhne archaeological survey of the Dingle Peninsula, though its local name appears in print at least as far back as 1939, when the writer and scholar known as An Seabhac cited it in his work on the place-names of the area. The earthen bank and a possible fosse, a defensive ditch dug outside the rampart, survive on the eastern approach. An eight-metre gap between the southern end of the bank and the cliff edge is thought to mark the original entrance. An Seabhac also noted the presence of a souterrain, an underground stone-lined passage of the kind found at many early medieval Irish sites, which reportedly ran from inside the fort out to an adjacent field. Such passages were used for storage, refuge, or escape, and their presence at a site is often taken as a sign of sustained occupation rather than purely seasonal or temporary use. A drystone wall running along the edge of the promontory may belong to a later, unrelated phase of use of the land.