Cathair an Éadain, anglicised as Caheraneden, translates roughly as the cashel of the brow or forehead, a reference to its position right at the lip of a ravine that drops away sharply to the west and north, falling to a depth of around ten metres. A cashel is a ringfort built from stone rather than earth, and this one sits at the plateau's edge as if it were designed to make the most of that natural defensive drop. The surrounding ground is thick with hazel and blackthorn, which adds to the sense of something half-swallowed by the landscape rather than simply ruined.

The structure itself is subcircular in plan, measuring roughly 32.7 metres east to west and 30.5 metres north to south. Its defining wall is double-faced, meaning it was built with an inner and outer skin of stone and a rubble core between them, a technique common in Irish early medieval construction. The outer face, composed of large horizontally laid stones, is visible all the way around, but much of the inner face and the lower portion of the outer wall are now buried under collapse, bringing the total width of the wall and its debris to somewhere between six and eight metres. A later drystone wall has been added along the western side, built directly onto the original outer face. The antiquarian Thomas Johnson Westropp noted the site's name and its topographic logic as far back as 1897, and it appears named on the Ordnance Survey six-inch maps of both 1842 and 1920. What makes the setting particularly dense with prehistory is the company it keeps: a megalithic structure lies roughly 22 metres to the east, and a court tomb, a type of Neolithic megalithic monument typically associated with communal burial, sits around 85 metres to the west-northwest. The cashel is itself part of a large multiperiod field system, meaning people were organising this plateau across many different eras, each generation leaving its own layer on the same ground.