The one at Glantane, in north County Cork, is considerably more elaborate. Set in pasture at a bend in a stream, above a steep-sided glen, it presents not one but a series of earthen banks and intervening ditches, or fosses, arranged around a circular interior measuring roughly 35 metres across. That multiplication of defences, unusual in itself, is further complicated by the awkward terrain the builders chose to work with.

A ringfort, sometimes called a rath, is essentially an enclosed farmstead of the early medieval period, typically dating from somewhere between the fifth and twelfth centuries. The enclosing banks were less about military fortification than about marking out a household's space and keeping livestock secure. At Glantane, the builders had to contend with a slope dropping away sharply into the glen to the north-west, which meant the banks on the western side had to be terraced down the incline rather than built to full height. The result is an asymmetrical arrangement: two banks with a fosse between them on the north-east to south-south-west arc, and three banks with two fosses on the south-south-west to north-east side, where the ground would have allowed for greater elaboration. The outer bank on that latter stretch still stands to around 0.9 metres, while the middle bank reaches 1.2 metres to the base of its fosse. Over time, the middle bank was absorbed into a later field boundary system, and a field boundary has also been cut through the banks to the west-south-west, the small intrusions of agricultural practicality that tend to accumulate around any earthwork left standing long enough. The interior itself tilts down toward the north-west, following the natural lie of the land toward the glen below.