Known locally as Dún Chonchúir, the cashel, which is an early medieval stone fort, measures roughly 69 metres north to south and 35 metres east to west, and its walls rise with up to three levels of internal terracing connected by steps, suggesting a structure built not merely to keep things out but to allow defenders to position themselves at height. The entrance faces east-north-east, and on the western side the inner rampart simply meets the edge of a low cliff, using the natural landscape as a continuation of its defences.

The cashel does not stand entirely alone in its defensive thinking. Traces of an outer rampart, considerably larger at around 110 metres north to south, survive in an arc from the north-west round to the south-west, though it disappears entirely on the western side where the cliff takes over. At the north-east, a subrectangular annexe partially overlies this outer wall and appears to have functioned as a forework, a kind of protective forechamber designed to guard what would have been the entrance through the outer rampart, though that entrance itself is now gone. Inside the main enclosure are the remains of several clochans, small dry-stone beehive huts that were a common form of early Irish domestic or ancillary structure. The site attracted scholarly attention as far back as 1886, and T. J. Westropp wrote about it in 1895, placing it within a longer tradition of interest in the Aran monuments. Much of the rampart visible today has been substantially restored, so what the eye takes in is partly reconstruction, though the underlying form and scale are genuinely ancient.