It takes a practised eye to read it: a very slightly raised oval of earth, barely half a metre above the surrounding pasture at its interior, ringed by a broad low bank of earth and stone. This is a rath, the most common type of early medieval enclosure found across Ireland, typically built as a defended farmstead for a single family and their livestock. What makes the one at Rahaberna quietly arresting is how little it announces itself, sitting almost flush with the wet ground around it.

The enclosure measures roughly 25 metres north to south and 23 metres east to west, making it a modest example of the type. The bank that surrounds it is about 3.2 metres wide but rises only 0.45 metres above the interior, suggesting either significant settlement over the centuries or an original construction that was never especially imposing. Outside the bank runs a fosse, the shallow ditch dug to provide the material for the bank itself, here about 4.7 metres wide and 0.4 metres deep. On the northern arc, between north-north-west and north-east, the bank disappears entirely and is replaced by a low scarp, a slight natural or worked edge in the ground just 0.2 metres high. A gap of about 3.5 metres in the bank on the south-east side is thought to be the position of the original entrance, which typically faced away from the prevailing wind and towards whatever path or track served the farmstead.