The site, officially recorded as DG078-039001, consists of a substantial sub-circular stone enclosure that has managed to survive despite the encroaching forestry. At least two gaps break the perimeter walls, and scattered stones suggest there may once have been a second outer enclosure or perhaps an elaborate entrance structure. Local tradition speaks of a summer house from the nearby estate that once stood in the vicinity, now lost beneath the trees; its builders may well have helped themselves to stones from the ancient cashel.

The souterrain itself remains in remarkably good condition, offering visitors a glimpse into how these underground passages functioned centuries ago. A stepped entrance descends into a main passage from which two chambers branch off at right angles, creating a classic T-shaped layout typical of these structures. The roof consists of massive flagstones, though time has claimed a few, leaving gaps in the ceiling. At the far end of the passage, opposite the entrance, an air vent provides crucial ventilation; a clever piece of engineering that kept these underground spaces habitable. Recently, protective fencing has been installed around the entrance, a necessary precaution given the development of new walking trails through the area, one of which now passes directly through the cashel grounds.

These souterrains, found throughout Ireland but particularly common in Ulster, likely served multiple purposes: storage for food and valuables, refuge during raids, or perhaps ritual spaces. The Gortletteragh example, with its protective cashel and well-preserved chambers, offers a tangible connection to the people who once called this landscape home, their lives shaped by the need for both community and security in an uncertain world.