What makes the structure quietly odd is not its condition but its placement: it sits roughly at the centre of a faint rectangular enclosure, the boundary of which has long since sunk beneath the grass, legible now only as a low trace of stone. The enclosure itself measures roughly 22 metres by 19 metres, and the building inside, with its double-faced wall construction and a southward-facing entrance, is just 7 metres long and 4 metres wide. Nobody has pinned a date to it with any confidence.

High Island, known in Irish as Ardoileán, sits off the Connemara coast and is associated primarily with an early medieval monastic settlement, the remains of which include an oratory, cells, and cross-slabs that draw most of the scholarly attention. The building described here, sitting a short distance south-east of the smaller of the island's two lakes, is noted by both R. A. S. Macalister and Michael Herity in their respective studies of the island, though neither assigns it a firm period. About 50 metres to the east, in a hollow along the same cliff edge, there is a level patch of ground enclosed by an intermittent low bank of stone, which may or may not be related. The double-faced wall technique, in which two parallel lines of stone face each other with rubble between, is a construction method found across many centuries in the Irish Atlantic tradition, which is part of why dating the structure remains elusive.

High Island is uninhabited and access is by arrangement with boat operators from the Connemara coast, typically weather-dependent and not straightforward. The monastic remains are the main draw for most visitors, but the southern cliff edge, where this building sits, rewards careful attention to the ground underfoot, where the grass-covered outlines of the enclosure wall are easier to read in low, raking light.