This is a rath, a type of ringfort typically built between roughly 500 and 1000 AD as an enclosed homestead for a farming family, defined by an earthen or stone bank that served as much as a social marker as a defensive one. What survives here at Rannagh is small but coherent enough to read.

The enclosure is roughly circular, measuring approximately 17 metres north to south and 15 metres east to west internally, dimensions that would have accommodated a family dwelling, perhaps a few outbuildings, and livestock pens within a bounded world no bigger than a generous back garden. The enclosing bank is best preserved on the western arc, where it still reaches an internal height of around half a metre and an external height of 0.7 metres, with a width of five metres at its broadest. More striking is the northern edge, where the ground outside the bank drops sharply by as much as 1.7 metres, suggesting either deliberate scarping or a naturally steep slope that was incorporated into the site's layout. On the north-north-east to east-south-east stretch, the bank has been considerably reduced, having long ago been absorbed into a roadside fence line. The interior tilts down toward the west and is heavily overgrown in the west-south-west to west-north-west portion. A second enclosure sits approximately 20 metres to the south-west, hinting that this was not an isolated dwelling but part of a small cluster of activity on this gentle rise, which commands clear views over lower ground from the north-west through to the south-east.