The first Ordnance Survey mapped it in 1834 as a circular earthwork, labelled in the gothic lettering reserved for antiquities as a "fort". By 1907 it had been redrawn as a small copse, the stones presumably obscured by encroaching vegetation. Neither label came close to what was actually there: seven megalithic chambers arranged across a roughly thirty-metre spread, some back-to-back, some facing outward in opposing directions, and divided partway along by a working farm laneway.

The structure belongs, or most likely belongs, to the class known as court-tombs, one of the oldest monument types in Ireland, typically dating to the Neolithic period and characterised by a roofed gallery of burial chambers set behind a semicircular or full forecourt. At Croaghan, the seven chambers follow the internal logic of court-tomb construction closely, with pairs of opposed and adjacent chambers that match the subsidiary sections found in known examples of the type. What is missing is the court itself, the open ceremonial space that usually anchors one or both ends of the structure. Whether it was never built, or has simply been lost to time and agriculture, is not known. A farm laneway now runs through the middle of the complex, separating four chambers to the SE from three to the NW, and the western group includes three upright slabs alongside one that has fallen. Two chambers at the northwestern end face each other across a gap of just 2.8 metres, their opposing entrances creating an arrangement that feels deliberate and strange in equal measure.

The site sits on grass-covered ground with some exposed rock outcrop and scattered trees towards the southeastern end of the ridge. The laneway that bisects it is still in agricultural use, which means the monument is effectively split between two sides of a working track, something worth bearing in mind when trying to take in the full extent of the chambers.