It sits on a prominent hill surrounded by undrained, uncleared marshy pasture, which means it has been left largely to itself, occupied now more by reeds than by any human presence. The name recorded on the 1916 edition of the Ordnance Survey six-inch map, Lisillaun, hints at its older identity, though the structure itself is far more ancient than any cartographic record.

A rath is an earthen ringfort, the most common monument type in the Irish countryside, typically dating from the early medieval period, roughly the sixth to the tenth centuries, and originally serving as a defended farmstead for a single family or small community. This one is almost perfectly circular, measuring 34 metres north to south and 33.5 metres east to west. It is defined by two concentric banks separated by an intervening fosse, that is, a ditch, which is still waterlogged. The inner bank stands up to 2.8 metres on its outer face; the outer bank is lower and more eroded, reduced to a mere scarp at the south where it has been further worn and overgrown. A causewayed entrance gap six metres wide on the eastern side marks the original way in, aligned as was common toward the rising sun. The 1840 Ordnance Survey already recorded the earthwork with hachures, the short lines surveyors used to indicate raised or banked ground, confirming the monument was well-preserved even then. A farmyard sits roughly 70 metres to the southwest, and the cattle gaps cut through the banks at three points suggest the fort has been folded quietly into agricultural routine for generations, its banks useful as enclosure long after their original purpose was forgotten.