It is not particularly large, but its layout is deliberate and quietly ingenious. The whole structure bends, narrows, and drops in ways that seem designed less for comfort than for control over who could move through it and how quickly.

A souterrain is an underground stone-built passage or chamber, constructed without mortar using a technique known as drystone walling, and found across early medieval Ireland typically in association with ringforts. This one consists of two chambers connected by what is called a drop-hole creep, a low constricted passage, just 0.78 metres high at its maximum, that forces anyone moving between the chambers to descend and squeeze through. The first chamber runs roughly east-west and measures 7.35 metres long and 1.29 metres wide, accessed through a small opening at its eastern end. Grassed-over foundation stones beyond that entrance hint that the chamber once extended further in that direction, its original length now lost. The connecting creep, 2.4 metres long and less than a metre wide, leads through the south-west wall into the second and slightly larger chamber, 8.25 metres long and 1.61 metres wide, which runs on a roughly north-south axis. The change in direction between the two chambers gives the structure its L-shape, a configuration that would have made rapid movement or pursuit through the underground space extremely difficult.

The souterrain sits within a ringfort, a type of enclosed farmstead typical of early medieval Ireland, usually defined by one or more circular earthen or stone banks. Underground passages like this one are thought to have served as storage spaces, refuges, or both. The precise function of any individual example is rarely certain, but the deliberate awkwardness of a drop-hole creep strongly suggests that ease of passage was not the priority.