In a field in Kilmanahan, County Waterford, a circular enclosure roughly fifty metres across exists almost entirely underground, invisible to anyone walking past it. The only way to see it is to look down from above, where the buried remains of a fosse, a defensive ditch dug around the perimeter of the site, cause crops growing overhead to behave differently from those in the surrounding soil. This differential growth appears as a cropmark, a faint but legible outline readable in aerial or satellite photography, and it is through that method that this particular enclosure came to light at all.

The site was identified and reported by Jean-Charles Caillère, working from satellite imagery captured by Maxar Technologies in 2021. Cropmark archaeology of this kind has transformed understanding of the Irish landscape over recent decades, revealing the outlines of enclosures, field systems, and other features that centuries of ploughing and land clearance have long since erased from the surface. A fosse-defined enclosure of this diameter is broadly consistent with a ringfort type, settlements built in their thousands across Ireland during the early medieval period, though without excavation the dating and function of this particular site remain open questions. Complicating the picture further, a field boundary cuts across the north-western portion of the enclosure, suggesting the original shape was disrupted at some point by later agricultural activity. A second, slightly smaller enclosure lies approximately 120 metres to the north-east, also visible only as a cropmark, raising the possibility that the two features were related or contemporary, though again that remains speculation rather than established fact.