The structure is a souterrain, a type of stone-lined underground chamber or tunnel built during the early medieval period, typically beneath or beside a rath, the circular earthen enclosure that served as a defended farmstead. What makes this example quietly remarkable is how intact it remains: more than thirteen and a half metres of drystone construction, every stone set by hand and held in place only by careful arrangement and the weight of what sits above.

The souterrain sits in the north-western quadrant of the rath and is laid out in two chambers running on different axes, connected by a creep, a deliberately low and narrow passage that forces anyone moving through it to crawl. The first chamber, entered from its south-eastern end, runs roughly east to west and measures just under four metres in length and just under two in width. At the northern end of its western wall, the creep begins: less than half a metre high, under a metre wide, and nearly two metres long. It opens into a second, larger chamber running roughly north to south, this one stretching to seven and a half metres in length, with a ceiling height of around one point seven metres, enough to stand in. The deliberate awkwardness of the creep is thought to be a defensive feature, slowing any intruder and leaving them vulnerable while those inside could move more freely. Whether these spaces were used for refuge, cool storage, or both remains a matter of interpretation rather than certainty.