The example at Ballythomas in County Tipperary sits on a gentle east-facing slope in undulating pastureland, and its dimensions have been measured in some detail: roughly 48.6 metres north to south and 45.6 metres east to west, making it a substantial example of the type. A bank, still standing to an internal height of around 1.3 metres, rings the interior, and beyond it lies an outer fosse, a defensive ditch cut into the ground, roughly six metres wide. The entrance, positioned in the south-east quadrant and nearly four and a half metres across, is flanked by boulders at the base of the bank, a detail that hints at deliberate construction rather than simple earthmoving.

A rath, as this class of monument is also known, was typically a farmstead of the early medieval period, roughly the fifth to twelfth centuries, enclosed by one or more earthen banks and ditches to define status and provide a degree of security for people and livestock. The Ballythomas example shows signs of later interference: in the northern and south-western sectors the bank has been cut back on its outer face, and earth and boulders have been tipped into the fosse at the northern side. This kind of truncation is common where farmland has been worked over many generations, with the earthwork gradually treated as a source of material or simply an obstacle to ploughing. The boulders at the entrance and those dumped into the ditch suggest that at some point the site was being actively modified rather than merely neglected, though the historical circumstances behind that activity are not recorded.