No walls, no timbers, no hearth stone breaks the surface of the rocky pasture. What remains is purely archaeological, a pattern of post-holes and slot-trenches recorded during excavation and since returned to the earth. Yet the absence is in itself the point. This is one of the best-documented Neolithic domestic structures in Ireland, a place where people lived, kept a fire, and organised their days, sometime in the centuries before 2000 BC.

The site, designated Site C House II, was uncovered in 1940 as part of a sustained campaign of fieldwork at Lough Gur led by Professor Seán P. Ó Ríordáin, whose excavations there ran across eighteen seasons and were published in 1954. The peninsula had already proved extraordinarily productive; Neolithic and Bronze Age remains cluster so densely around the lake that the area constitutes one of the most significant prehistoric landscapes in the country. House II sat roughly seven metres north-west of a companion structure, House I, and its oval footprint measured approximately 7.6 metres by 6.5 metres externally. The walls were a hybrid construction, paired upright posts supplemented by wattle panels and sections of plank-built walling set into a slot-trench, a technique that suggests considerable practical knowledge of timber building. Four large post-holes slightly off-centre within the floor are thought to have supported the roof. A shallow sunken hearth, just fifteen centimetres deep, was recorded on the north-west side. A possible entrance on the south side was compromised by a pit cut directly across it, leaving the question unresolved. Archaeologist Rose Cleary revisited and described the structure in detail in 2018, noting that nineteen additional post-holes within the floor area formed no clear pattern, their purpose still unknown.

The site itself carries a quiet complexity for the visitor: it does not appear on Ordnance Survey Ireland historic maps, and aerial orthoimages taken between 2005 and 2013 show nothing. Only a faint trace of the excavation grid is visible on a Google Earth image from June 2018. The landscape around it, however, remains legible. Adjacent sites excavated by Ó Ríordáin lie within fifty metres to the south-west and twenty metres to the north-east, and a stone circle known as Circle K sits about ninety metres to the north-north-west. Anyone approaching across the rocky pasture of Knockadoon is effectively walking through a layered prehistoric settlement, most of which sits just below the grass.