What makes this particular example quietly interesting is a practical piece of ancient engineering: the interior has been deliberately raised on its southern side to level out the natural fall of the hillslope, so that whoever lived within it had something approaching a flat floor rather than a tilted one.

The site is a rath, the Irish term for a ringfort, the most common type of early medieval settlement monument in the country. Typically dating from roughly the fifth to the twelfth century, raths were enclosed farmsteads, their circular earthen banks offering a degree of protection for a family and their livestock. At Ballyduhig the enclosure is roughly circular, measuring about 40.6 metres east to west and 36.9 metres north to south. The defining element running from the south-west around to the east-south-east is an earthen bank standing about 1.35 metres high; elsewhere the boundary takes the form of a scarp of similar height, where the ground has simply been cut back into the slope rather than piled up. A shallow external fosse, a defensive ditch, survives on the northern side. Together these features describe a settlement that was carefully adapted to its particular piece of ground rather than simply imposed upon it.