The place is known locally as Cathair an Dúin, which translates roughly as the fort of the stronghold, and the name alone hints at a layered significance that the earthworks themselves confirm.

The site is a promontory fort, a form of coastal enclosure common along the western seaboard in the early medieval period, where a natural cliff face does much of the defensive work and human effort is concentrated on the landward approaches. Here, that effort was considerable. The main defensive line is a revetted scarp, meaning a steep earthen or stone-faced slope reinforced to prevent collapse, rising to nine metres in height. Behind it lies a fosse, a defensive ditch running between six and ten metres wide, with an outer bank beyond that. A slight rise along the fosse and a gap in the bank suggest that an entrance causeway once crossed at roughly the midpoint of the enclosure, giving controlled access into an interior measuring about ninety metres by fifty. Near the cliff edge in the south-eastern corner, two low grassy banks running east to west are likely the faint remains of a structure, possibly a hut or small building, reduced over centuries to barely legible humps in the turf. Then, at the western end of the same enclosure, stand the remains of a Second World War lookout post. Ireland's wartime neutrality, known officially as the Emergency, included a coastwatching service that stationed observers at points around the coastline, and this headland, commanding wide views of the Atlantic approaches, was an obvious choice. The result is a site where prehistoric or early medieval defensive thinking and mid-twentieth-century military pragmatism arrived independently at the same conclusion about the value of this particular piece of ground.