In a field near Ardglass in north County Cork, a circular enclosure of roughly twenty metres across falls into that second category. No visible earthwork survives at ground level. What we know of it comes from a cropmark, the phenomenon by which buried ditches and pits cause the vegetation above them to grow differently, revealing their outlines to an aerial camera when conditions are right. In this case, the photograph was taken in July 1989 as part of a systematic aerial survey, and what it captured was the ghostly fosse, or defensive ditch, of a circular enclosure with what appears to be an entrance on its eastern side.

The site belongs to a class of monument sometimes called a ring-ditch, a term that can cover several different original functions, from enclosed settlements to ceremonial or funerary sites, though the specific purpose of any given example is rarely certain without excavation. What adds a layer of interest here is the presence of a second circular enclosure roughly ninety metres to the north-north-east. Whether the two were contemporary, or even related in use, is unknown, but their proximity in the landscape is suggestive of a locality that saw repeated or sustained activity at some point in the prehistoric or early medieval past.