The rath at Tomboholla, Co. Mayo survives only as a rough semicircle; quarrying has eaten away the northern and eastern arc, and a road now runs along where the bank and fosse once completed the circuit. What remains, though, sits on a natural rise in open pasture, with streams to the east and south-west, a positioning that would have made practical sense to whoever enclosed this ground more than a thousand years ago.

Raths, the earthen ringforts that survive in their tens of thousands across Ireland, were typically the enclosed farmsteads of early medieval families, their low banks and ditches marking out a domestic space rather than a fortification in any serious military sense. The Tomboholla example is modest in scale, roughly 29 metres on its longer axis and 22 metres on the shorter, with an earthen bank that stands only about 0.2 metres above the interior ground level but drops more steeply on the outside to a height of around 1.4 metres. That asymmetry is worth noting: the visible height from outside would have given the enclosure more presence than the gentle interior rise suggests. Beyond the bank, a fosse, essentially a ditched depression, runs around the curving edge, between 2 and 2.5 metres wide, shallowing and widening towards the north-west where it becomes harder to read. A barely perceptible linear rise outside the fosse at the north-west may represent a second, outer bank, though it could equally be the trace of an old field boundary.

The damage is layered and cumulative. A straight field fence cuts across the eastern side of the rath, truncating it on a north-north-west to south-south-east line. The quarrying that removed the northern arc was a separate event again, leaving the remaining earthworks ringed with dense brambles and gorse that now define the perimeter more clearly, in a rough way, than the surviving bank does. The result is a site that reads as a landscape anomaly, a semicircular rise that seems slightly out of place in its field, until you trace the fosse and begin to reconstruct what the full circuit would have looked like.