The hillock itself is roughly circular, and on its crown sits an enclosure of similar shape, measuring approximately twenty metres north to south and seventeen metres east to west. What defines it is a combination of a sod-covered stony bank along the western and northern sides, and a scarp, a natural or shaped slope cut into the ground, running around the northern and south-eastern arc. Where the scarp meets the hillock, the two features blur together, making it difficult to say with confidence where the human-made ends and the natural begins. The interior, whatever its original purpose, is level.

Enclosures of this kind are scattered across the Irish landscape and can date from prehistory through to the early medieval period. They were used for a wide range of purposes, from settlement and stock management to ritual activity, and without excavation it is rarely possible to say which function applied in a given case. At Larkhill, the bank survives to an external height of just over a metre and a third, with the internal face considerably lower at roughly half a metre, suggesting the original ground level inside was raised, or that material was piled outward. The stony core beneath the sod hints at deliberate construction rather than a simple earthen dump. The combination of bank and scarp to define a boundary, with the hillock itself providing the platform, points to someone choosing this particular rise in the ground with some care.