This one at Caherlissakill is not hiding anything any more. The souterrain here is fully exposed to the sky, its roofing gone except for two stone lintels still resting at its eastern end, which makes it unusually legible as a structure. A souterrain is a dry-stone-built underground passage, typically associated with a ringfort, and thought to have served for storage, refuge, or both. Here, rather than appearing as a sealed mystery beneath the ground, the whole thing can be read from above, its roughly Z-shaped course tracing across the slope like a diagram of itself.

The passage sits within the north-eastern quadrant of a ringfort, on ground that falls away steeply to the south-east. That slope is not incidental to the structure; the souterrain follows the lie of the land so closely that its south-eastern end sits around 3.5 metres below the level of its north-western end. In plan, the passage runs north-east to south-west for around 10.5 metres, then turns onto a north-west to south-east axis for another 7.4 metres, before a final eastward section of 6.5 metres, giving the whole thing a distinctly angular, jointed character. The passage is around 2.1 metres wide throughout. That combination of significant width and a descending, multi-directional layout, adapting to slope rather than cutting through it, is what gives this particular example its quiet structural interest.