On a low ridge in Trantstown, County Cork, one of these earthworks survives in reasonable shape, its double-bank arrangement still readable across the pasture where cattle now graze.

The fort is what archaeologists call a bivallate ringfort or rath, meaning it has two concentric earthen banks rather than the single bank more commonly encountered across Ireland. These circular enclosures were typically built during the early medieval period, roughly between the fifth and twelfth centuries, and functioned as defended farmsteads for a family of some local standing. At Trantstown, the inner bank survives to about 1.75 metres in height and encloses a roughly circular area measuring approximately 45 metres north to south and nearly 44 metres east to west. Between the two banks lies a fosse, essentially a ditch, and there are faint traces of a possible outer fosse to the west as well. The outer bank, standing around a metre high, is stone-faced in parts, which sets it apart slightly from purely earthen examples. A formal entrance breaks through both banks to the north-northeast, the inner gap around five metres wide and the outer a little narrower at four metres, with slight traces of a causeway crossing the fosse. The ridge position is deliberate; the site commands open views to the west, north, and east, which would have made it easier to monitor the surrounding land.

What gives the site its particular character is the proximity of a second bivallate ringfort just twenty metres to the southeast. Two ringforts of similar construction placed this close together is not an everyday arrangement, and likely reflects some kind of deliberate pairing, perhaps associated with related households or a subdivision of landholding at some point in the early medieval period. Today the interior is largely level, aside from some dumped spoil, and the banks are covered in scrub. A cattle gap has been cut into the western side, a practical intrusion that is common enough on earthworks that have remained in agricultural use.