A cashel is simply a ringfort built from stone rather than earthen banks and ditches, a logical choice in a landscape where limestone sits at the surface and soil is thin. This one at Ballymurphy measures roughly 40 metres north to south and 36 metres east to west, its enclosing wall now reduced to a collapsed ridge of drystone rubble about two metres wide and less than a metre high in most places. What survives most legibly is the southern stretch, where the inner and outer faces of the wall can still be distinguished, the horizontally laid stones still roughly in position after what may be more than a thousand years of slow subsidence.

The enclosure sits within a multiperiod field system, meaning the landscape around it was being divided, worked, and reworked across several distinct eras, and the cashel itself may reflect more than one phase of use. Inside the walls, the foundations of a possible hut sit near the centre, and several other small structures cluster against the inner wall-face at the west, the south-west, and the north-east corners. These are thought to be possibly secondary additions, built or modified after the main enclosure was already established. The north-east structure is particularly small, its interior measuring only about 1.2 metres in each direction, suggesting a storage or ancillary function rather than habitation. The whole complex sits in rough pasture on the limestone pavement, the characteristic exposed karst surface of the Burren, where the rock fractures into flat slabs divided by narrow fissures called grikes, making the ground both visually striking and awkward to cross.