Somewhere beneath the overgrowth covering its eastern half, a circular earthen bank traces the outline of a rath, the Irish term for a ringfort, one of the most common archaeological features in the Irish countryside. These were enclosed farmsteads, built mainly during the early medieval period, in which a family and their livestock lived within a raised bank, and sometimes a surrounding ditch. At Cappagh, that bank still follows its original circuit to a diameter of roughly 32 metres, and there are traces suggesting it may once have been faced, or revetted, with stone to give it added stability and permanence.

When a researcher named Neary recorded the site in 1914, the picture was somewhat clearer. He noted both an enclosing bank and an outer fosse, the term for a defensive ditch dug around the perimeter of such a structure. That fosse has since vanished entirely from view, absorbed back into the surrounding grassland over the intervening century. What Neary catalogued as a circular earthen fort is now a site where the archaeology is present but partial, legible only in outline. Adding a further layer of interest, a second ringfort lies approximately 100 metres to the south-west, raising the possibility that these two enclosures once formed part of the same farming landscape, their occupants neighbours in the early medieval world.