This is a rath, the Irish term for a ringfort, the most common type of early medieval settlement monument in the country. Thousands were built across Ireland, mostly between roughly 500 and 1000 AD, serving as enclosed farmsteads for a single family or small community. That familiarity makes them easy to overlook, yet the one at Bohonagh repays a closer look simply because its proportions are so well preserved.

The enclosure is almost perfectly circular, measuring 32.5 metres across in both directions. An earthen bank, still standing around three metres high on the interior face, defines the boundary, and beyond it runs an external fosse, a defensive ditch cut into the slope to a depth of about 1.5 metres. The fosse survives on the south-east to south-west arc of the circuit, where the ground conditions have protected it from agricultural levelling. Two gaps interrupt the bank: a wider break to the east, roughly six metres across, and a narrower one to the west at just over three metres. One of these almost certainly marks the original entrance; the other may be a later breach, though without excavation it is impossible to say which is which. The interior, slightly raised above the surrounding field, would once have contained timber structures, a well, perhaps small outbuildings, all long gone.