It does not announce itself as a raised earthwork or a visible ring of stones. Instead, it exists most clearly from the air, revealed only when crops grow unevenly across the buried outline of its walls, producing what archaeologists call a cropmark, a difference in the colour and height of vegetation that betrays what lies beneath the soil.

The enclosure is oval in shape, measuring roughly 25 metres by 20 metres, and sits on a gently north-east-facing slope, with steeper ground rising to the east. Cropmarks of this kind typically indicate a buried ditch or bank, the remains of a structure that has been absorbed so completely into the landscape that centuries of ploughing or grazing have levelled any surface trace. Oval enclosures in Ireland are often associated with early medieval settlement, sometimes marking the boundary of a farmstead or a small defended homestead, though without excavation it is impossible to say what purpose this particular one served or when it was built.

What makes it quietly compelling is precisely that invisibility. The aerial photographs that revealed it show a ghost pressed into the earth, a shape that has outlasted whatever stood inside it, legible only to those looking at the right angle, at the right time of year, from far enough above the ground to see the whole thing at once.