The one at Cornastauk, sitting low in the marshy grassland of the Bonet River valley in County Leitrim, does almost none of that. Its earthen bank is so worn and overgrown that on the eastern side it has flattened almost entirely into a scarp, a gentle slope in the ground rather than any recognisable wall. There is no fosse, the defensive ditch that typically rings such enclosures, and no trace of a formal entrance. It is, in short, the kind of site that asks you to look very carefully before you see it at all.

A rath, as this type of earthwork is commonly called in Irish contexts, is a roughly circular enclosure built during the early medieval period, typically between the fifth and twelfth centuries, and used as a farmstead or small defended settlement. Thousands survive across Ireland in varying states of preservation, but the conditions here in Cornastauk have not been kind. The site sits on the valley floor of the Bonet River, a north-south watercourse in County Leitrim, with a stream running roughly a hundred metres to the east. That low, wet, marshy setting is likely part of the reason the earthwork has subsided and spread so dramatically over the centuries. The interior diameter of the enclosure, measured north to south, is approximately 24.5 metres, which would have been a reasonably substantial space, but the bank that defines it now barely rises more than 40 centimetres above the surrounding ground on its outer face, and just 10 centimetres on the interior. What was once a deliberate boundary has become barely a rumple in the grass.