At Kilkilleen in County Cork, a shallow depression in the south-eastern quadrant of a ringfort is the only visible clue that a souterrain may lie beneath the ground. A souterrain is an underground stone-lined passage or chamber, built during the early medieval period, typically associated with ringforts and used for storage, refuge, or both. Here, the earth itself has settled slightly over what might be one, leaving a faint surface hollow as the sole suggestion of something below.

The ringfort with which this possible souterrain is associated sits at Kilkilleen, and the depression in its interior is tentatively interpreted as marking the position of a buried underground structure. The qualification matters: this is a may rather than a confirmed find. No excavation record in the available material confirms the souterrain's existence. It remains a site defined by potential rather than certainty, the kind of place that archaeology sometimes leaves suspended between discovery and conjecture.