It is easy to overlook, given the scale of the cashel, a substantial dry-stone ringfort, surrounding it, but this modest building may have served a very specific function: controlling who passed through.

Hugh O'Neill Hencken, excavating at Cahercommaun in 1938, identified the structure as a guardhouse, labelling it Structure 1 in his published account of the site. The positioning supports this reading. It sits immediately south of the entrance passage to the inner enclosure, placed exactly where someone tasked with monitoring or restricting access would need to be. A further passageway to the east, designated Structure 2 by Hencken, is thought to have provided access directly into this guardroom, a detail examined more closely by Claire Cotter in her 1999 analysis of the site. Cahercommaun itself is a multivallate cashel, meaning it has multiple concentric stone enclosures, perched on the edge of a cliff in County Clare's Burren landscape. It has been a national monument in State care for some time, which has helped preserve the complex arrangement of structures within its walls.

The guardhouse, taken on its own, is a small thing. But set in context, positioned at a chokepoint within a fortification already designed around layers of controlled access, it speaks to a fairly considered approach to security among whoever built and occupied the site. The Burren's limestone plateau preserves such details well, and Cahercommaun rewards the kind of attention that goes beyond the obvious drama of its cliff-edge setting.