The enclosure measures roughly 48 metres north to south and 53 metres east to west, with a two-metre gap opening to the south, most likely the original entrance. It is, in all probability, a ringfort, the most common type of early medieval monument in Ireland. Ringforts, which typically date from around the fifth to the twelfth centuries, were enclosed farmsteads, the low banks marking out a family's living space and providing some protection for livestock against wolves and raiders. Thousands survive across the country, yet the sheer ordinariness of that description can make it harder, not easier, to appreciate what you are looking at.

The site sits within the landscape surrounding Lough Mask and Lough Carra in County Mayo, an area surveyed in 1994 by the Lough Mask and Lough Carra Tourist Development Association, with the enclosure at Bunnadober recorded as entry 411 in that survey. The earthen bank, worn down over centuries of agricultural use, is modest by any measure, yet its circular form has persisted through the landscape long enough to be plotted and described. The southern gap is a detail worth noting; many ringforts share this orientation, possibly for practical reasons related to the prevailing wind, or simply by convention that accumulated across generations of builders who had learned from one another.