What remains is the eastern portion of a small rectangular or square building, tentatively identified as an oratory, a term used for the modest, single-roomed prayer cells associated with early Irish monasticism. It sits positioned between a burial ground and a leacht, which is a low commemorative cairn or stone structure traditionally linked to a saint or sacred figure, an arrangement that suggests the site once formed part of a coherent early Christian enclosure.

The surviving masonry is notable for its quality. The walls, averaging 1.1 metres in width, are described as well-built, and the internal measurement of 3.3 metres running northeast to southwest gives some sense of the building's original compactness. Structures of this kind, when intact, would have been among the smallest and most austere forms of religious architecture in early medieval Ireland, designed less for congregation than for solitary or small-group devotion. The Iveragh Peninsula, on which Killogrone sits, is known to contain a significant concentration of such early Christian remains, reflecting the intensity of monastic activity along the western seaboard in the early medieval period. The precise date of this particular building has not been established from the available record, and only the eastern portion of the structure has been recorded, leaving the full extent of the original plan uncertain.