At its centre are the low, unassuming footings of a rectangular prehistoric house. What makes the arrangement quietly remarkable is not the house itself, which survives only as a scatter of stones and shallow earthen banks, but its relationship to the enclosure around it. The house entrance lines up almost exactly with the enclosure entrance, and the building sits at the precise centre of the ring. That alignment is not coincidence; it is the strongest argument that the two structures were planned and used as a single unit.

The enclosure, listed in 1912 by Windle as Circle K, is the largest of its kind on Knockadoon, measuring some 31 metres in diameter. It consists of two concentric rings of stones set close together, with the gap between them packed with rubble, forming a kind of thick stone wall rather than two separate features. An entrance passage on the eastern side was found, during excavation by Séan P. Ó Ríordáin in 1940, to have held four wooden posts at its ends, suggesting a substantial timber structure, possibly a gate. The house inside, recorded as House No. 2, was roughly 8.2 metres by 6.4 metres. Its walls survived only as low footings, varying in construction around each side: a double row of stones on the northeast, single rows elsewhere, with natural rock outcrops incorporated into the south-western footing where the ground allowed. Post-holes cut into the bedrock traced the positions of upright timbers along three of the four walls, and two larger holes near the centre of the building may have carried roof supports. There was no internal fireplace. A second structure, House 1, was also found on the site, though it lay outside the enclosure and without its protection.

The site is part of a dense cluster of prehistoric monuments around Lough Gur, and a standing stone and a further enclosure lie approximately 85 metres to the south-south-east. A visitor approaching across Knockadoon will find the remains low to the ground and easy to miss without some foreknowledge of what to look for; the wall footings are modest, and what survives above ground gives little immediate sense of the scale described by excavators. The clearest feature to orient yourself by is the enclosure's outer ring of stones, which retains enough of its circuit to give a sense of the original 31-metre diameter. The post-holes and finer internal details are not visible without excavation, but standing inside the enclosure and tracing where the house once sat, with the lake spread out below, gives a reasonable sense of the deliberate geometry that prehistoric builders imposed on this particular corner of the hillside.