A souterrain, or underground passage, extends northward from what appears to be an unremarkable depression in the ground. This subterranean structure once connected to a destroyed cashel; a type of circular stone fort common in early medieval Ireland. Today, only a curving modern wall hints at the western section of the original fortification, but the souterrain itself remains largely intact, offering a glimpse into how our ancestors built defensive and storage structures centuries ago.

The main passage stretches seven metres towards where the cashel once stood, though loose stones and soil now block its northern end. Built using traditional drystone construction techniques, the walls support nine flagstone slabs that form the roof, creating a space roughly one metre wide and 0.8 metres high. Two smaller passages branch off to the west from the main tunnel. The first, located 2.3 metres from the entrance, measures just 55 centimetres wide and 40 centimetres high, roofed with four flagstones and extending three metres before encountering another blockage. The second western passage, found 5.6 metres from the entrance, is even more cramped at only 25 centimetres high, though slightly wider at 65 centimetres, and runs for two metres under two flagstone slabs.

Originally accessed through a small aperture measuring 33 by 65 centimetres, now blocked with stones, the souterrain would have served multiple purposes for the cashel's inhabitants. These underground passages typically functioned as hiding places during raids, storage areas for food and valuables, or escape routes in times of danger. The site occupies high ground that slopes towards the south and west, a strategic position that would have given the original cashel's defenders clear views of approaching threats, though today the area has been significantly altered by modern construction.