No earthwork rises above the flat ground here, no visible bank or ditch breaks the surface, yet from the air a faint ring emerges in the soil, the ghost of an enclosure approximately forty metres across. This is what aerial archaeology calls a cropmark, the phenomenon where buried features cause overlying crops or grasses to grow differently, revealing their outlines to a camera overhead when the conditions are right. The circular fosse, a defensive ditch dug around a settlement, shows up in photographs taken in June 2004, its presence registered not by anything you could trip over, but by the differential growth of plants responding to what lies beneath them.

The site belongs to the category of monument known as a ringfort or rath, the most common type of early medieval settlement in Ireland. Typically dating from roughly the fifth to the twelfth centuries, ringforts were enclosed farmsteads, their inhabitants protected by one or more earthen banks and ditches. The low-lying, level ground at Ballyhealy, within earshot of the sea, would have offered both accessibility and exposure to whoever once lived within this particular enclosure. The proximity to the shore is notable; coastal locations were not unusual for such settlements, offering access to marine resources alongside the more typical agricultural activities associated with rath dwellers. The site itself has left no dramatic surface trace, its ditch long since silted and levelled by centuries of cultivation and weather.