It sits on the south-western side of a narrow gravel ridge, a slightly raised and flat-topped ring roughly twenty-four metres across, defined by a low scarp that barely reaches forty centimetres in height. A mortared stone wall encircles it at a little distance, oak trees ring the inner scarp, and a few Scots pine grow inside among the stumps of others long since felled. The structure is tidy in its geometry and utterly ambiguous in its purpose.

The 1838 Ordnance Survey six-inch map recorded it simply as a circular enclosure, offering no interpretation. By the 1922 edition, the interior had been walled off and planted with trees, suggesting that whoever managed the Castlehill estate at that point had decided the feature was more useful as an ornamental tree-ring than whatever it had been before. The question is whether they were repurposing something genuinely ancient or creating a landscape feature from scratch. A rath, the Irish term for a roughly circular earthen enclosure typically associated with early medieval settlement and farmsteads, would leave precisely this kind of low, rounded footprint after centuries of weathering. The scarp and the few protruding stones along its rim are consistent with that reading. But they are also consistent with a purely decorative planting feature built to give structure to a nineteenth-century demesne landscape. No excavation has resolved the matter, and the two possibilities have never been ruled out. The enclosure sits in that uncomfortable space between prehistory and garden design, and the ground itself is not talking.