This is Killelehy Fort, a rath, which is to say a roughly circular enclosure built during the early medieval period, typically as a farmstead or place of local importance, defined by raised earthen banks and ditches. What makes this particular example quietly interesting is how selectively it has survived: the inner scarp, the raised inner edge of the enclosure, can still be traced from the south-west around through north to south-east, but the fosse, the encircling ditch, and the outer bank beyond it are only discernible along the western side. The rest has been quarried away, most likely for building material at some point during the demesne's active life, leaving roughly half the monument intact and the other half essentially absent.

The earthwork measures approximately 27 metres on its north-east to south-west axis and 25 metres across from north-west to south-east, making it a fairly typical example of its type in terms of scale. It sits within what was once the designed landscape of Eyrecourt Demesne, the estate associated with the Eyre family, whose house at Eyrecourt was one of the notable late seventeenth-century country houses of Connacht. The relationship between the demesne's woodland and the rath is one of slow enclosure; the trees that now make the monument difficult to read are also, in a sense, what has kept the remaining earthwork from further disturbance. Dense overgrowth has both obscured and, arguably, preserved what quarrying left behind.