This massive pear-shaped enclosure, covering roughly 10 hectares, consists of two stone ramparts that follow the natural contours of the hilltop, offering commanding views across the surrounding countryside. The ramparts, constructed primarily of stone and earth, are most impressive on the northern and northwestern sides where they reach up to 16 metres in width and nearly 3 metres in height.

What makes Rathcoran particularly fascinating is its layered history spanning thousands of years. At the summit sits a Neolithic passage tomb, excavated in the late 1930s by archaeologist Walshe, which predates the hillfort by millennia. The tomb is now protected by a substantial drystone wall built from stones that once formed its covering cairn. Modern surveys using GPS, LiDAR, and geophysical techniques have revealed up to fifty circular hut platforms scattered throughout the interior, evidence of substantial occupation during the Iron Age.

Despite its impressive scale, Rathcoran may never have been completed. Archaeologists have noted the unfinished nature of sections of the ramparts and the presence of quarry pits between the banks, suggesting the builders may have abandoned their work before the defences were fully realised. The hillfort forms part of the Baltinglass cluster, one of nine similar monuments in the area, representing one of the most significant concentrations of Iron Age defensive sites in Ireland. Today, much of the interior lies hidden beneath dense gorse and scrubland, adding an air of mystery to this ancient stronghold.