Near Dunmore in County Kilkenny, on a natural terrace running north to south along the eastern edge of the Nore and Dinin river valleys, a roughly circular enclosure of around 35 metres in diameter sits in otherwise ordinary farmland, under grass and tillage, entirely invisible to anyone standing on the ground. It was not excavated or surveyed on foot but spotted through a phenomenon known as crop-marking, or wind-flashing, whereby variations in buried soil and archaeology cause overlying crops to grow or ripen at slightly different rates, producing ghostly outlines that only become legible from altitude. This particular outline appeared on an aerial photograph taken on 16 July 1971.

Crop-mark sites of this kind are relatively common across the Irish midlands and river valleys, where centuries of ploughing have levelled earthworks that were once substantial. The enclosure at Dunmore sits on a terrace with good views to the west, where the land falls away to the flood plain of the Nore, a position typical of enclosed settlements throughout the early medieval period, when a slight elevation above wet ground provided both drainage and visibility. Roughly 20 metres to the southwest, a ring-ditch has also been identified, a circular trench that may represent a prehistoric burial monument, suggesting the area carried significance across more than one period. The two features together hint at a landscape that was used, and reused, over a very long span of time.