Somewhere along the east-west route that cuts through Tarmon in north Kerry, tarmac and roadbed have obliterated whatever earthworks once formed the southern arc, leaving only the northern semicircle to hint at what was once a complete and substantial ringfort.

What survives is classified as a bivallate platformed rath, meaning it was originally defended by two encircling elements, a fosse and an outer bank, and that the interior sits noticeably higher than the surrounding ground, a platform effect that would have given both physical and psychological advantage to whoever lived or gathered there. A rath is a ringfort of earthen construction, one of the most common monument types in the Irish landscape, typically associated with early medieval settlement between roughly the fifth and twelfth centuries. This one is not small: the internal diameter runs to 28 metres east to west, and the inner area rises 1.7 metres above the fosse, which itself measures around 5 metres across. The outer earthen bank reaches 2 metres in height on its external face. Modern steps have been cut into the raised platform area to the north-north-east, a practical intervention that signals the site remains accessible, even if its geometry is permanently halved. The structure was documented in the North Kerry Archaeological Survey, compiled by C. Toal and published in 1995, which recorded its condition and dimensions in detail.

The surviving northern arc is worth examining closely precisely because the truncation makes legible what is usually buried or gradual. The relationship between the raised interior, the wide fosse below it, and the outer bank beyond becomes almost diagrammatic when you can see the earthwork in cross-section, as the road has inadvertently forced here. The stepped access to the north-north-east makes the platform reachable without damaging the bank itself.