It has no dramatic stonework, no tower, no ruin in the conventional sense, just a low earthen bank tracing an almost perfect circle roughly thirty-one metres across, with a narrow gap on the eastern side that once served as an entrance. This is a ringfort, or rath, the kind of enclosed farmstead that tens of thousands of Irish families lived within during the early medieval period, roughly the fifth to twelfth centuries. The "rath" element of the place-name Rathmoyle is a direct marker of that origin, a linguistic fossil pressed into the map.

What survives at Rathmoyle is modest but legible. The enclosing bank varies in width from around six metres on the east side to ten metres on the south, and rises between roughly half a metre and one and a half metres depending on where you measure it. Unusually, there is no visible fosse, the external ditch that typically accompanies such banks and from which the material for construction was usually quarried. Its absence here is a small puzzle. The entrance, three metres wide, opens to the east, which is consistent with a common preference in ringfort construction, possibly practical, possibly shaped by older beliefs about orientation. On the western perimeter, the clarity of the bank is interrupted by spoil from a lime-kiln positioned at the south-west. Lime-kilns, stone or brick structures used to burn limestone into quicklime for use in agriculture and building, were a feature of the eighteenth and nineteenth century rural economy, and their builders were not always squeamish about raiding older earthworks for convenient material or simply dumping nearby.