The example at Cahirguillamore in County Limerick does something different. There is no bank here at all. Instead, a flat circular platform of earth, roughly fifty metres across, sits slightly raised above the surrounding ground, defined not by a wall or rampart but by a water-logged fosse, the term for a defensive ditch, that rings it completely. The entrance is a narrow causeway on the north-east side, and just outside the ditch to the south-west, a small pond sits fed by an underground spring. The whole thing occupies low, wet ground, and the waterlogged fosse is less a constructed defence than a condition the landscape itself imposes.

The monument was described by O'Kelly in 1942 to 1943, who noted the platform stands roughly 1.2 metres above the fosse bottom, giving it a modest but deliberate elevation above the soggy terrain. The absence of a bank is the detail that sets it apart from the more familiar rath type, where an earthen rampart would typically enclose a farmstead of the early medieval period. Here, the geometry is the same, the circular form, the single causewayed entrance, but the means of enclosure is entirely hydraulic. Whether the water in the fosse was a natural consequence of building on wetland, or was deliberately managed, O'Kelly does not say, though the presence of a spring-fed pond immediately outside the ditch suggests the hydrology of this particular patch of Limerick was always a defining feature of the site.

Cahirguillamore sits in low-lying farmland, and the wet ground that O'Kelly described in the early 1940s remains characteristic of the area. Visitors approaching across the fields should expect soft ground, particularly after rain, and the fosse itself is likely to retain water through much of the year. The platform, 50 metres in overall diameter, is visible as a distinct, flat-topped rise once you are close enough, though from a distance it can read simply as a slightly elevated field. The causeway on the north-east gives the clearest sense of how the site was originally accessed, a narrow dry approach threading between the water on either side.