The souterrain, an underground stone-built passage or chamber system commonly associated with early medieval Irish settlement and used for storage or refuge, was infilled after its investigation and leaves no visible trace on the surface above it. It is, in effect, a significant piece of underground architecture that has been returned entirely to the earth.

The structure came to light in 1929 and was subsequently investigated by Somerville, whose findings were published in 1930. What he documented was considerable: five chambers cut from bedrock, each roofed with a barrel vault, and fitted with wall recesses that may have served as shelving or niches. The original entrance was at the southern end of the first chamber, with three rock-cut steps descending from the surface, though the 1929 access point was a breach through the roof of the third chamber. Four air vents kept the system breathable. Most intriguing is the feature extending northward from the fifth and final chamber: a deep, narrow rock-cut trench running 12.2 metres, at the base of which a flat-bottomed trough was recorded, measuring roughly 45 centimetres deep and 45 centimetres wide. Its purpose is not explained in the available record, and that ambiguity gives the whole structure an additional layer of interest. McCarthy, writing in 1977, also documented the site, suggesting it continued to attract scholarly attention decades after its discovery.

Because the souterrain has been infilled and carries no surface trace, there is nothing for a visitor to observe at ground level. Its interest lies entirely in the documentary record it left behind, a detailed picture of a type of structure that survives in fragments and partial glimpses across early medieval Ireland, here preserved only on paper.