What makes it particularly intriguing is the density of what lies inside: not just an enclosing bank but the faint remains of at least two internal structures and, most strikingly, the ruined traces of a souterrain, an underground stone-lined passage of the kind associated with early medieval settlement in Ireland, where such tunnels likely served as storage spaces or refuges. The outer bank itself has been absorbed into the local field system over time, its earthen core given an external stone facing and pressed into service as an ordinary boundary wall, which is part of why it registers more as a feature of the farming landscape than as an ancient monument.

The site appears as "Blackquarter fort" in gothic lettering on Ordnance Survey six-inch maps from both 1834 and 1907, suggesting it was already recognised as something older and worth marking, even as its fabric was being quietly altered. It is a rath, the type of enclosed farmstead that was the dominant form of rural settlement in early medieval Ireland, typically defined by one or more earthen banks and an internal fosse or ditch. Here, no fosse is visible, and while there are entrance gaps at the west, north-west, and south-east of the enclosure, none can be identified with certainty as the original. Inside the bank to the north-north-west, a D-shaped platform roughly three metres across may represent the remains of a hut-site. At the centre of the enclosure, the foundations of a subcircular structure some four metres in diameter survive as a low bank with a narrow entrance at the south-west. The souterrain, now largely destroyed, once comprised a roughly oval chamber approximately four and a half metres by three and a half metres, with a passage extending south-westward for around nine metres before turning south for a further seven and a half metres, running close to the inner edge of the enclosing bank.