A large rectangular enclosure, roughly 90 metres east to west and 45 metres north to south, lies on a gentle north-east-facing slope at Killilagh, visible not as a dramatic earthwork but as something far more subtle: a low surviving bank along its south-western edge, and elsewhere as a cropmark, the kind of faint discolouration in growing vegetation that reveals buried features to aerial photography long after they have vanished at ground level.

The enclosure was reported by Conn Herriott, and its clearest traces were confirmed through aerial imagery captured between 2011 and 2013. The south-western corner is the most legible portion, with around 14 metres of the south-west side and some 47 metres of the south-east side still distinguishable. Rectangular enclosures of this kind in Ireland are associated with a range of uses across many centuries, from early medieval settlement and agricultural organisation to ecclesiastical precincts, and the proximity of Killilagh graveyard, lying just 70 metres to the south-west, raises the possibility of a connection between the two. Graveyards in rural Ireland frequently preserve the outlines of much earlier enclosed sites, sometimes monastic, sometimes secular, their boundaries shifting and contracting over time while the land around them continued to be farmed.