At Reenroe in County Cork, a field of level pasture holds no visible sign of what nineteenth-century cartographers recorded there, yet the maps insist something once stood, or curved, or enclosed a space that mattered to someone.

When the Ordnance Survey produced its six-inch map of the area in 1842, the surveyors marked a semicircular enclosure using hachures, the short radiating lines used to indicate an earthen bank or raised feature on the ground. By the time the same area was mapped again in 1902, only an arc of bank was shown, suggesting the feature had already diminished considerably in the intervening sixty years. Today, there is no visible surface trace at all. The enclosure at Reenroe belongs to a category of site that archaeology sometimes calls a cropmark candidate or a ghost feature, something whose physical form has been absorbed back into the land through centuries of cultivation, settlement, and the slow work of weather. Enclosures of this general type in Cork and across Ireland were variously used as farmsteads, pastoral boundaries, or ceremonial spaces, though without excavation it is impossible to say what purpose this particular one served or when it was built.