This is a rath, the Irish term for a ringfort, the type of enclosed farmstead that was built in great numbers across Ireland during the early medieval period, roughly between the fifth and twelfth centuries. Thousands survive across the island in varying states of preservation, but this one at Killea sits high enough to command views in every direction, a quality that would have made it a desirable location for whoever chose to build here.

The enclosure measures fifty-six metres across from north to south, defined by a scarp, essentially an earthen bank or slope, that still stands between one and one and a half metres above the surrounding ground on its outer face. Beyond that scarp runs a fosse, a rock-cut or dug defensive ditch, roughly three and a half metres wide and half a metre deep, which survives best along the southern and western arcs of the circuit. A gap on the south-western side is thought to mark the original entrance, the point through which people, animals, and goods would have passed in daily life. Along the eastern face of the scarp, there is evidence of stone revetment, meaning that at least part of the earthen bank was faced or reinforced with stone, a detail that hints at a degree of care and investment in the structure's construction and upkeep. Whether the interior was ever excavated, and what might lie beneath the raised ground within, remains unrecorded here.