A rath is an earthen ringfort, typically dating from the early medieval period, and this one is bivallate, meaning it has two concentric banks rather than the single bank seen at simpler examples. What sets it apart from the other six raths in the same townland is a third, external fosse, a ditch cut into the ground on the outer edge, running from the ESE around to the south. That feature appears nowhere else among this local cluster, and the wide berm, roughly twelve metres of level ground sitting between the inner fosse and the outer bank, was noted as unusual for Clare forts as a whole.

The antiquarian Thomas Johnson Westropp recorded the site in 1909, measuring the banks at between five and eight feet in height and observing their steep profile. He also identified it, with reasonable confidence, as the place referred to in seventeenth-century records as 'Doonaghbwee Caghir', a property held by one Teige O'Cahan in 1655, in what was then recorded as the townland of 'Balleonan', since merged with Doonaghboy. The fort's dimensions are considerable: an interior measuring roughly thirty-four metres north to south, with an overall spread of around seventy-five metres when both banks and ditches are included. The construction varies across the circuit, with gravel making up the outer bank to the east and earth and stone used to the west. At the ESE, water that collects in the two fosses escapes through a narrow channel cut across the field, a small but telling sign that whoever built this place gave some thought to drainage as well as defence.