This rectangular earthwork runs northwest from the castle site, stretching approximately 25 metres in length and 20 metres in width. Though time and cattle have taken their toll on the structure, leaving it quite denuded and poached, it still presents itself as a slightly raised area bounded by a low scarp that rises between 0.4 and 0.7 metres above the surrounding landscape.

The most distinctive feature of this site is found along its southeastern side, where traces of a shallow outer fosse, or defensive ditch, can still be detected. This ditch measures about 1.1 metres wide and 0.3 metres deep, providing tangible evidence of the defensive nature of the structure. Bawns were fortified enclosures typically built adjacent to tower houses and castles in Ireland, serving as secure areas where livestock could be protected and where the castle’s supporting community could retreat during times of conflict.

While the remains at Kinnafad may not be immediately impressive to the casual observer, they represent an important piece of Ireland’s plantation period landscape. The connection to Kinnafad Castle and the defensive features still visible in the earthworks offer a glimpse into how landowners once organised and protected their holdings in this part of County Kildare, when the threat of raids and the need for defensive structures shaped the very layout of the countryside.