The mound, roughly four metres by two, sits atop what was once the bank of a ringfort, and a capstone at its eastern end sits probably directly above the largest of three subterranean chambers. The ringfort itself, known locally as 'The Raheen', was reportedly ploughed out around a century before the underground structure was found, leaving this buried architecture as the sole surviving element of what had been a more complex site.

A souterrain is an underground passage or chamber, typically stone-lined, built during the early medieval period in Ireland and associated with nearby ringforts. Their precise function remains debated, though storage, refuge, and cold-keeping for foodstuffs are the most commonly cited possibilities. The Raheen example was discovered in 1972 and subsequently investigated by Ellen Prendergast for the National Museum of Ireland. What she found was a carefully engineered sequence of three chambers connected by two narrow passages and oriented roughly east to west, the whole thing cut into the earth and stone-lined throughout. The first chamber, oval in plan, was relatively compact, with vertical flagstones lining its lower walls and a corbelled roof of small flagstones and boulders above. A well-constructed portal passage, barely 60 centimetres high and 45 centimetres wide, led westward into the second chamber, which was pear-shaped and slightly larger, roofed with flat lintels. From there, a long curved sloping passage, retained by drystone walling and a lintelled roof, descended to the third and largest chamber: an oval space five metres long, two metres wide, and one and a half metres high, built with upright slabs, corbelling, and lintels. At its north-western angle, a blocked portal extends further, and it is unclear whether this once led to another chamber or to the original entrance of the entire souterrain.

The site sits on a steep east-facing slope in undulating terrain, currently under pasture. The entrance mound on the old bank remains visible, and the capstone at its south-eastern end gives a rough sense of the scale and position of Chamber 3 below. The blocked north-western portal, still unresolved, leaves open the possibility that the known extent of the souterrain is not its full extent.