The site, known in Irish as Cill Ó gCróin, is not a ruin in the singular sense; it is an accumulation of overlapping phases, all compressed into a roughly oval enclosure measuring about 40 metres north to south and 52 metres east to west. What survives above ground is largely a band of collapsed stone, averaging around a metre and a half wide and a metre high, with some original outer facing of large boulders still visible at the north-east. Inside this boundary, the concentration of features is considerable: two leachta (low stone cairn-like structures associated with veneration, typically marking the graves of saints or holy figures), seven drystone buildings including one that may be an oratory, a burial area, and an ogham stone, a pillar carved with an early medieval Irish script, which is cross-incised and stands on one of the leachta. A cross-slab formerly stood there too, though it is no longer present.

The internal arrangement offers glimpses of a complex history. The south-east quadrant is partitioned off from the rest of the enclosure by a separate, poorly preserved wall, part of which is formed from upright slabs set end-to-end. This inner division appears to pre-date the main enclosure wall, which seems to overlie it at one end, suggesting the site was built up and reorganised over time rather than laid out in a single plan. A modern trackway running north-east to south-west now cuts through the enclosure, separating most of the features to its east from two of the drystone buildings to its west. Just outside the enclosure, there are the remains of what may have been a horizontal mill, a simple water-powered grain mill of a type commonly associated with early Irish monastic settlements, where a horizontally mounted wheel was driven directly by a fast-flowing stream without the need for gearing. That combination of oratory, leachta, burial ground, ogham stone, and possible mill places Killogrone firmly within the pattern of small, self-sustaining religious communities that once occupied the more remote parts of the Iveragh peninsula.