The one at Ballymartin, County Limerick, does the opposite. It occupies a low-lying, marshy field, and instead of relying on height for its defence, it was ringed with water. Two of its three fosses, the defensive ditches that encircle the earthen banks, are still waterlogged today. The middle fosse widens to four metres on the western side. Whatever family or farming community built this place evidently decided that wet ground was as good a barrier as any hilltop.

A ringfort, or rath, is essentially a circular enclosure defined by one or more earthen banks and ditches, used in early medieval Ireland primarily as a farmstead and place of shelter. What makes the Ballymartin example notable is its concentric complexity. The circular interior measures roughly 31 metres north to south and 30 metres east to west, defined by a scarped inner edge, and is then wrapped by two further earthen banks with two intervening fosses and an external fosse beyond those. The interior itself, still under pasture, dips down towards the centre, suggesting the ground has never been built over in any substantial way since the site was in use. A deliberate entrance survives at the northwest, where a four-metre break in the outer bank lines up with a causeway crossing the middle fosse and a corresponding shallowing of the inner fosse, the kind of careful arrangement that implies a well-used, formal approach. The site was recorded and compiled by Denis Power, with details uploaded to the national record in August 2011.

The earthworks are in variable condition. The scarp along the southern arc is the best preserved section, while the northwestern stretch has been denuded and partially cut through by a later field boundary, which crosses the middle fosse and skirts the inner bank. The northeastern side is heavily masked by overgrowth. Visiting in late winter or early spring, before vegetation thickens, would give the clearest sense of the banks and their profile. The waterlogged fosses are a practical warning as much as a historical detail; the ground around this site is genuinely soft, and the marshy character that made it defensible centuries ago has not entirely disappeared.