The site is gone now, built over under planning reference F13A/0248, but the excavation record it left behind is quietly extraordinary. What made it unusual from the outset was what was absent rather than what was present. No hearths, no post-holes, no evidence of houses or workshops inside the enclosure boundary. Just a large sub-square ditch, roughly 39 by 50 metres, with an entrance facing north-northeast, and a ditch packed with animal bone.

The enclosure was excavated in full by archaeologist Gill McLoughlin of Courtney Deery Heritage Consultancy Ltd. under licence 16E0101, and radiocarbon dating placed its main period of use between the late 7th and late 9th centuries AD, though an internal curving ditch, whose lower fill dated to between 347 and 43 BC, indicated that the site had been in use since the Iron Age. The ditch itself varied considerably in width, from 2 metres to nearly 5 metres, and in its deepest waterlogged sections either side of the entrance, organic material had survived, including a wooden hoop of yew fastened with a leather tie. Cattle bone dominated the animal assemblage at over 60 per cent, a proportion higher than is typical for the period and strongly suggestive of feasting. Two finds stood out among the rest: a Romano-British socketed iron knife blade, and a copper-alloy pin with a baluster head, a spiral ring, and a spatula-shaped projection decorated with engraved interlace. According to the typological work of T. Fanning, such spiral-ringed baluster-headed pins originated in Ireland in the late 4th or early 5th century AD, likely produced by craftsmen working from Roman or sub-Roman prototypes, and this particular example, with its dot decoration and engraved interlace, has no close parallel in the archaeological record. Two further enclosures were subsequently excavated in the same field, 130 metres to the northeast and 150 metres to the southeast, both yielding similarly high concentrations of cattle bone and imported early medieval pottery. Together with a nearby burial, an upstanding mound, and the proximity of the site to the estuary, the cluster has been interpreted as a possible assembly landscape, a place where communities gathered periodically for feasting, exchange, and perhaps the conduct of social or political affairs.

There is nothing to see at the site today. The enclosure was entirely removed during excavation in advance of the residential development, and the houses now occupy what was once a significant piece of ground. The northern portion of the adjacent Phase 1B enclosure survives within a buffer zone around the Portmarnock mound, which remains upstanding, though it sits within a modern suburban setting. The finds from the excavation, including the unique decorated pin, were submitted to the National Monuments Service, and the full excavation report by McLoughlin was completed in 2019. The value of this site lies now entirely in its documentation, a detailed record of a place that gathered people across many generations and left almost no trace above ground even before the diggers arrived.