The structure is a souterrain, a type of man-made underground passage or chamber system associated with early medieval Irish settlement, typically built to serve as a cool-storage space, a refuge, or both. What makes this one quietly interesting is not just its survival but its layout: three distinct chambers connected by creepways, low narrow passages through which a person would have to crawl, each room slightly different in shape and scale, and each dropping a little further into the earth.

The souterrain was discovered and recorded in July 1983, sitting within what is thought to be the northern half of a ringfort, the circular enclosed farmstead that was the dominant settlement form in Ireland from roughly the fifth to the twelfth century. The construction technique here is partly rock-cut, meaning the chambers were carved directly into bedrock up to the level of the curved roof, which was then finished in earth rather than stone. The first chamber is oval in plan, roughly 2.6 metres by 2.1 metres, and its floor was found covered in debris. A short creepway leads north into a second chamber with a roughly triangular plan, reaching up to three metres in length and 1.2 metres in height, with an air vent set into its western corner. From there, a longer creepway descends eastward into a third and larger chamber, rectangular in plan at approximately 3.8 metres by 1.7 metres, with a blocked construction shaft at its northern end. That shaft is a detail worth pausing on: it was likely used during the original building work to remove spoil and then sealed once the souterrain was complete, a small trace of the practical problem-solving involved in digging out a hidden underground space by hand.