The rath at Killeenduff is barely twenty metres across, a modest roughly circular platform raised only slightly above the surrounding pasture on a gentle west-facing slope. Yet running along the base of its enclosing earthen bank, on both the inner and outer faces, are limestone slabs set upright on edge, a technique known as revetment, used to retain and stabilise the bank material and prevent it from slumping outward over time. Most ringforts rely entirely on piled earth or on a combination of earth and a surrounding ditch, called a fosse, but here the fosse has either never existed or has long since been levelled to nothing. What remains is a low bank, just three metres wide and a quarter of a metre high, held in place by carefully placed stone.

Ringforts, or raths, are among the most common archaeological monument types in Ireland, with tens of thousands recorded across the country. They date broadly to the early medieval period, roughly the fifth to the twelfth centuries, and are generally understood as the enclosed farmsteads of farming families, their banks and ditches marking a boundary between domestic and agricultural space rather than functioning as serious military defences. The limestone revetment at Killeenduff survives best along the south-east to south-south-east arc and at the north-west, which gives some sense of where the original construction was most robust or where later disturbance has been least severe. One notable feature is a substantial quarry hole running along the inner foot of the bank from the north-east around to the south-east, measuring eighteen metres in length and six metres wide, sunk to a depth of around half a metre. Whether this hollow is connected to the original sourcing of the limestone slabs used in the revetment, or represents later agricultural activity, is not clear, but it is conspicuous enough to read plainly in the landscape.