The site sits strategically with the Kings River flowing roughly 80 metres to the north and northeast, whilst a smaller stream branches off to the west, running 20 metres south of the fortification before rejoining the main river to the southeast. The bailey stands elevated above the surrounding island, which appears prone to flooding; the marshy ground around its base has long since been reclaimed. Though the position offers commanding views east and west along the valley floor, rising ground to the north and south limits visibility in those directions.

The bawn follows the perimeter of an earlier bailey that adjoins a motte, likely constructed by Geoffrey FitzRoberts in 1192-3 when he established the town of Kells. Historical records from the early 13th century mention ‘castelli’ at Kells, probably referring to a timber castle that once crowned the motte. After the FitzRobert lordship ended around 1308-1312, the site passed through various absentee lords including the le Poers, Berminghams, and Prestons, before coming under the control of Thomas Butler, prior of Kilmainham, in the 15th century and eventually the Viscounts Mountgarret in the 16th and 17th centuries. An inquisition from 1621 references a ‘fortilagium’ at Kells, which may relate to the surviving bawn structure.

Today, the limestone rubble walls of the bawn, standing 4 to 5 metres high and roughly 0.9 metres thick, survive in two main sections along the southeast and southwest quadrants of the bailey. The southwest wall incorporates the gable of what may have been the gaol marked on early Ordnance Survey maps; this later addition features three narrow defensive loops at first floor level within splayed embrasures, and remnants of a vaulted ceiling. Put log holes punctuate the walls throughout, evidence of the scaffolding used during construction. The bailey extends westward from the motte as a raised platform, defined by a scarp ranging from 3 to 5.2 metres wide and 1.85 metres high. Though no trace remains at ground level of the masonry castle that may have stood within the bawn, the surviving walls offer a tangible connection to eight centuries of Irish history, from Anglo-Norman conquest through centuries of changing lordships.