The enclosure measures 28.5 metres across, defined by a bank roughly a metre high and a shallow external fosse, the ditch dug around the outside to throw up the bank material during construction. What makes it quietly remarkable is its ordinariness: cattle graze inside it now, just as people and their livestock likely sheltered within a similar enclosure in the early medieval period.

This is a rath, the most common type of ringfort in Ireland, typically built between the sixth and tenth centuries as a defended farmstead for a single family and their animals. Thousands were constructed across the country, though many have been levelled by ploughing or development over the centuries. The Fornaght example survives in reasonable condition, its circuit largely intact apart from a break in the bank on the eastern side, which may mark the original entrance, as east-facing openings are common in Irish ringforts, possibly oriented toward the rising sun. The interior, kept short by grazing animals, would once have contained a house, outbuildings, and perhaps a souterrain, an underground stone-lined passage used for storage or refuge, though no such features are mentioned here.