The earthen bank and fosse, the defensive ditch that would have circled the entire enclosure, has been nearly erased on most sides, worn down over the centuries into little more than a subtle rise in the ground. From the south-south-east around to the west, however, the fosse survives as a narrow, deeply cut, waterlogged trench, still holding its shape after perhaps a thousand years. That contrast, between the vanished and the stubbornly present, gives the site an odd quality, as though the landscape has selectively remembered it.

Ringforts, also known as raths, are among the most common archaeological monuments in Ireland, typically dating from the early medieval period, roughly the sixth to the tenth centuries. They functioned primarily as enclosed farmsteads, with the surrounding bank and ditch marking out a family's territory and providing some degree of security for livestock. This example at Corbeagh has an internal diameter of 24.6 metres, a fairly typical size. A break in the bank on the south-east side may mark the original entrance, and a large stone lying on the surface within the interior adds a point of quiet curiosity; whether it is structural, incidental, or something brought there long after the fort was in use is not recorded. A second break in the bank, on the west-north-west side, leads into a shallow circular depression of unknown purpose, sitting just inside the line of the bank. Its significance remains unexplained.