This is a souterrain, an underground stone-lined chamber of the kind built throughout early medieval Ireland, most commonly in association with raths, the circular earthwork enclosures that once served as farmsteads for farming families of middling status. What makes this one worth noting is how well it has survived.

The chamber is drystone-built, meaning its walls were constructed without mortar, the stones carefully selected and laid to hold themselves in place through weight and friction alone. It runs on a northwest to southeast axis, measuring more than 7.2 metres in length, and retains a blocked creep in its northwest wall. A creep is a deliberately small, low opening connecting one chamber or passage to another, sized to force anyone entering to move slowly and with difficulty, which suited its likely purposes of refuge and concealed storage. The souterrain sits within the rath recorded as GA027-030, and both features together represent the kind of enclosed early medieval settlement that was once common across the Irish countryside, though far fewer survive in this condition.