This is a rath, the Irish term for a ringfort, the kind of roughly circular enclosed settlement that was built across Ireland in the early medieval period, broadly between the fifth and twelfth centuries, and used primarily as a farmstead by a single family or small community. Thousands survive in various states across the country, yet each has its own particular character, and the one at Rabaun is unusually legible in what it still shows of its original layout.

The enclosure is subcircular, measuring roughly 26.5 metres north to south and 30 metres east to west. Its defining bank, composed of gravelly earth and topped with stones, survives to an external height of 1.4 metres on the western side, though the interior face is much lower, only around 0.3 metres above the domed interior ground level. Outside the bank runs a fosse, a defensive ditch, still traceable as a shallow depression around the eastern arc and partly preserved in outline by a later field wall that curves around the monument at a distance of about three metres. That a field wall should follow the arc of an ancient fosse so precisely is itself a small curiosity, suggesting that farmers working this land centuries after the rath fell out of use still recognised its boundary as something worth respecting. A gap of about 1.8 metres in the bank at the south-south-east likely marks the original entrance. At the centre of the domed interior, a faint mossy circle roughly five metres in diameter is just visible, its purpose uncertain. Two shallow depressions sit near the inner edges of the bank, and a later drystone structure, small and square, abuts a field wall that now crosses the interior. A stream meanders through damp ground about a hundred metres to the north, and the townland boundary follows its course, a reminder that water and territory have been neighbours here for a very long time.