The structure is a cashel, the term used for a stone-walled ringfort, and what makes this one at Ballygastell quietly puzzling is that despite measuring nearly nineteen metres across, nobody looking at it today can say with confidence where you were supposed to walk in. Several gaps and breaks interrupt the perimeter wall, but none of them reads clearly as an original entrance.

The cashel is subrectangular in plan, running approximately 18.6 metres east to west and 17.6 metres north to south. Its wall, built from upright limestone slabs and loose boulders, averages about a metre in width, though it stands only 35 centimetres above the interior ground level and 65 centimetres on the outside, suggesting significant collapse and centuries of slow subsidence into the pasture. No dressed wall-facing survives, which makes it harder to read as a built structure rather than a natural scatter of rock. Inside the eastern half, two internal divisions complicate the picture further: a squared-off area roughly 8.6 metres on each side to the north, defined by a collapsed and now grass-covered wall, and a smaller rectangular space to its south. These subdivisions hint that the interior was organised and used in ways that went beyond simple enclosure, though what those uses were remains open. The cashel sits within a much larger multiperiod field system, meaning the landscape around it carries the marks of human activity from several different eras layered on top of one another, the stone walls and divisions of one generation quietly absorbed into the next.

The Burren's limestone plateau makes this part of Clare a landscape where ancient structures survive unusually well, the thin soils and sparse tillage having left stonework largely undisturbed. At Ballygastell, the rough pastureland and outcropping rock mean the cashel blends into its surroundings with considerable ease, its walls low enough to read as field boundaries to an inattentive eye.