It measures roughly 24 metres across and is enclosed by an earthen bank still standing around two metres high, with a fosse, that is, a defensive ditch, cut one metre deep into the ground on the outer side. The symmetry of it, preserved in a working field, is what catches the attention: the shape has outlasted whatever once stood inside it by well over a thousand years.

This is a rath, the most common type of ringfort found across Ireland, typically dating from the early medieval period, roughly the fifth to the twelfth centuries. Raths were enclosed farmsteads, most likely home to a single family and their livestock, the bank and fosse providing a deterrent against cattle raiders rather than a fortification in any military sense. The earthen construction is straightforward, which is partly why so many have survived: there is nothing to quarry, no dressed stone to repurpose. At Madranna, the bank runs from the southern to the eastern arc of the enclosure, with the external fosse still legible in the ground below it. The interior dimensions, close to circular and just under 24 metres on both measured axes, are broadly typical of the type, though even modest variations in size and construction can reflect differences in the status or wealth of the families who built them.