Cropmark evidence, visible in aerial photography, outlines a roughly circular univallate enclosure, meaning a single-ditched ring, approximately 70 metres in diameter. What makes it unusual is not the enclosure itself, common enough in early medieval Ireland, but an 'avenue' feature attached to its eastern entrance: two parallel ditches running outward from the opening, forming a kind of formal approach corridor that has few obvious parallels in the immediate area.

Two phases of test excavation, carried out ahead of proposed development, gradually filled in the picture. The first, conducted under licence number 00E0732, confirmed the ditch, the entrance, and the presence of archaeological material on both sides of the main enclosure boundary. Among the finds was a decorated bone bead. The second phase, licence number 07E0547, opened sections across the enclosure ditch and the avenue. The enclosure ditch itself was substantial, around 7 metres wide and 2 metres deep, and its fills contained charcoal, butchered animal bone, and a considerable quantity of sea shell, including oyster, mussel, razor shell, periwinkle, and cockles. The lower deposits were waterlogged, preserving lenses of decayed wood and grass. A charcoal sample taken from the primary fill returned a radiocarbon date of AD 687 to 887, placing occupation firmly within the early medieval period. The southern avenue ditch, when excavated, proved similarly filled with shell, animal bone, and charcoal, suggesting sustained activity rather than a single episode of use.

The site sits on the western end of an east-west ridge, with open views across towards the coast and Ireland's Eye. At present it is fenced off within overgrown wasteland, not accessible to casual visitors, though the Portmarnock South Local Area Plan intends that the buffer zone around the monument will eventually be incorporated into a green infrastructure network. Those with an interest in the site can appreciate its ridge-top position and coastal aspect from the surrounding area, and the excavation reports are publicly accessible through the excavations.ie database, where Christopher Moriarty's 2008 entry provides the fullest account of what lies beneath the surface.