But from the air, the enclosure at Lisnagrough resolves into something altogether more deliberate, a roughly circular form roughly forty metres across from north to south and thirty-two metres from east to west, its outline betrayed by a patch of grass growing differently from its surroundings, the kind of differential growth that aerial photography has long been used to detect in Irish fields.

The enclosure sits on an undulating plateau, positioned at the edge of a steep natural slope that falls away to the north towards a stream below. The boundary is formed partly by a low earthen bank, the sort of modest raised ring associated with enclosed farmsteads or ring forts that were common across Ireland from the early medieval period, and partly by the natural scarp of the hillside itself, which does the work of a bank along the north-western to north-eastern arc. The internal height of the earthen bank measures around 0.6 metres, while the external face stands at only 0.18 metres above the surrounding ground, suggesting considerable time and agricultural activity have worn it down. A ring fort, or rath, of this kind would typically have enclosed a family farmstead, with the bank and any accompanying ditch providing a degree of security for people and livestock alike. Here, the landscape itself was clearly part of the logic of the site, the steep drop to the north offering natural protection that reduced the need for as much constructed earthwork on that side.