The ditch itself was up to 5.5 metres wide and 1.65 metres deep, large enough to have made an impression on anyone approaching from the outside. What made the site unusual was not simply its size but what had been discarded into that ditch over the centuries: imported pottery from the eastern Mediterranean, worked antler, cereal-drying kilns, evidence of metalworking, an enormous quantity of animal bone including whale bone, and a single adult male burial radiocarbon dated to somewhere between AD 410 and 607. There were no signs of ordinary domestic life. Whatever was happening here, it was not quite everyday.

The enclosure, excavated in 2016 by Gill McLoughlin of Courtney Deery Heritage Consultancy Ltd under licence 16E0613, turned out to be one of at least three closely related enclosures in the same field near Station Road, Portmarnock, with a fourth a further 550 metres to the southeast in Maynetown. Earlier aerial photographs, including a Google Earth image from July 2006, had revealed it as a cropmark, the kind of faint discolouration in growing crops that betrays a buried ditch or bank below the surface. Eight distinct phases of activity were identified across the site, running from the Mesolithic through to the early medieval period, though the bulk of the material clustered in the late Iron Age and early medieval transition, roughly AD 400 to 600. The imported pottery, known as LRA 1 and E ware, points to connections with the late Roman world at a time when such goods were reaching only a handful of high-status sites in Ireland. The very high proportion of cattle bone, mirroring what was found in a neighbouring enclosure 130 metres to the southwest, is consistent with large-scale feasting rather than routine food preparation. McLoughlin's 2019 report proposed that this cluster of sites, taken together with an upstanding mound immediately to the north, should be understood as a possible assembly landscape, a place where people gathered periodically for social, political, or ceremonial purposes rather than one they actually lived in.

Most of the enclosure no longer exists above or below ground. The excavated portion was built over as part of a residential development, and only the northern arc of the ditch survives in situ, preserved within a 20-metre buffer zone around the adjacent mound, which the old Cassini edition Ordnance Survey maps marked simply as a 'Mote'. That mound and its immediate surroundings have been laid out as a green space with a play area and information signage, and the line of the buried ditch is traced in the hard and soft landscaping around it. A visitor who knows what to look for can read something of the enclosure's curve in the way the ground has been shaped, though the full extent of what once stood here now exists only in the excavation report.