The rath at Ballynascubbig in West Cork is more elaborate than that. It has two concentric earthen banks, the outer one actually slightly taller than the inner, the gap between them measuring 16.5 metres. That space between the rings was not wasted ground; in early medieval Ireland, where these enclosures were typically built and occupied between roughly the sixth and tenth centuries, the area between a double ring of banks, known as a berm, would have housed livestock, provided a buffer against raiders, or simply signalled the status of whoever lived within. A double-banked ringfort, sometimes called a bivallate rath, was a mark of some standing.

The enclosure sits on a north-east-facing slope in pasture, its circular interior measuring 35 metres north to south and 34 metres east to west. The inner bank stands 1.6 metres high and is accompanied by a shallow external fosse, which is the ditch from which the bank material was originally dug. The outer bank, at 1.8 metres, is the taller of the two. Both rings have gaps at various points: the inner bank opens to the east, south, and west; the outer to the east, south-east, and north-west. Some of these breaks will be original entrances, though others may have been made in later centuries by farmers moving livestock or machinery through the site. The rath has survived in reasonable condition, which is not always the case in Cork, where agricultural pressure has levelled many comparable monuments.