A cashel is a ringfort built from dry-stone walling rather than earthen banks, and this one uses its natural setting with a degree of calculation that is still readable in the surviving masonry. The quarry immediately below the wall was almost certainly the source of the stone used to build it, and its presence added to the structure's already formidable defensive profile on that side, combining an engineered wall with a sheer rock face beneath it.

The cashel is roughly circular, measuring just over twenty-one metres north to south and a little over twenty metres east to west, with walls between three and three and a half metres wide. Closer inspection of that wall reveals two distinct phases of construction. The original circuit, one to two metres wide, followed the standard Burren cashel form: two stone faces with a rubble core between them. At some later point an additional skin of coursed masonry and rubble, also one to two metres wide, was added to the interior face. The two phases can be distinguished by their different surviving heights, the outer original section standing up to 1.4 metres and the later inner addition reaching only 0.2 to 0.4 metres above the interior ground level. This technique of layering internal facings connects the cashel to what researchers have described as the "Western Stone Fort" tradition seen at comparable sites in the Burren, such as Ballykinvarga and Cahercommaun, and on the Aran Islands. The south-south-east entrance, 1.15 metres wide, is flanked by large upright slabs rising above the wall line, and a substantial stone lying outside it is most likely one of the two fallen lintels recorded by the antiquarian Thomas Westropp in 1911, who noted the gateway as being of the normal type with coursed jambs. The original doorway passage, at 4.3 metres long, appears to have been square-headed. Westropp also identified the site as Caheridoula, the name giving the townland of Cahermacnaghten its title, though this identification was erroneously transferred to a different cashel some 220 metres to the south-west on the 1920 Ordnance Survey edition. To the south-east, roughly 58 metres away, a cluster of ruined houses and a house site have been associated with the cashel, as has a garden or plot to its south-west, suggesting that the enclosure formed part of a wider settlement landscape that extended well beyond its walls.