The enclosure measures roughly 38 metres across at its widest and retains a clearly defined entrance gap, two metres wide, in its north-western side. A shallow outer fosse, the ditch that typically accompanies such earthen enclosures, runs around the outside, though it has been worn down considerably and reads now more as a faint depression than a purposeful feature. The interior, level and enclosed, is notably waterlogged.

What makes the site at Kilknockan particularly interesting is the relationship between this early enclosure and a later medieval ringwork that cuts across its southern side. A ringwork is a type of fortification, broadly comparable to a motte-and-bailey castle but without the raised mound, consisting instead of a ditched and banked ring used as a defensible enclosure. The evidence at Kilknockan suggests this ringwork was not placed here by accident. Whoever constructed it appears to have chosen the spot deliberately, taking advantage of the earlier earthwork already on the ground and most likely using the original enclosure as a bailey, the outer courtyard or defended yard that typically adjoined a medieval fortification. The older bank and fosse were, in effect, pressed into service centuries after they were first raised, their useful shape more important to a later occupant than their original purpose.