For generations of map-readers, this site at Drumnagoal simply did not exist on paper. It was only through aerial photography that the outline became legible, the kind of discovery that has added dozens of sites to the Irish archaeological record in recent decades.

A ringfort, or rath, is an enclosed farmstead of early medieval date, typically defined by one or more circular earthen banks and used as a defended homestead for a family and their livestock. The example at Drumnagoal sits on a level terrace along the north-east-facing slope of a low ridge. Its plan is subcircular, measuring roughly 27 metres on the north-east to south-west axis and 25 metres on the north-west to south-east. The enclosing element varies around its circuit: a low bank of earth and stone, between 1.6 and 2.6 metres wide and standing to a height of between 0.6 and 0.8 metres, runs from the north-west around through north to the south-east, while elsewhere the boundary relies on a natural or cut scarp rather than a built-up bank. A break of about 2 metres in the bank on the north-east side may mark the original entrance. A field boundary running roughly north-north-east to south-south-west now cuts across the interior, dividing the enclosed area into two unequal portions, a common fate for earthworks that have been absorbed into later agricultural landscapes.