That ambiguity is, in its own way, the point. The feature, roughly circular and approximately fifteen metres in diameter, appears on the first edition Ordnance Survey six-inch map of 1840, drawn at a time when surveyors were recording what they observed on the ground. Today, nothing of it is visible at ground level, and the marshy, poorly drained terrain in which it sits is not the kind of place where early enclosures, typically the circular earthwork boundaries associated with farmsteads, burial sites, or ritual use in early medieval Ireland, tend to turn up. That combination, a cartographic ghost in an unlikely location, makes it genuinely puzzling.