The one at Carrowneden, in County Sligo, went considerably further. Sitting at the south-western foot of a north-west to south-east ridge, amid ordinary pasture, this earthwork presents three concentric banks, each separated by its own fosse, enclosing a raised circular interior just 22 metres across. The outermost bank alone stands over two metres high on its exterior face. For a relatively modest enclosure, the defensive architecture is notably elaborate.

A ringfort, or rath, is a circular enclosure built in earth or stone, most commonly during the early medieval period in Ireland, roughly between the fifth and twelfth centuries. They served as farmsteads, the banks and ditches offering protection for people and livestock rather than signalling any great military ambition. The triple-bank form at Carrowneden is far less common than the standard single-bank variety and suggests that whoever built it either had particular reason to invest in its defences or possessed the social standing to command the labour required. The innermost bank runs to 4.4 metres wide, with the interior surface raised 0.7 metres above it on the inside and 1.8 to 2.3 metres on the exterior, the height varying between the southern and northern sections. Beyond that, two further banks step outward, each fronted by a fosse, a word for the ditches dug to provide the material for the banks above them. The original entrance, oriented to the east-north-east, survives as a two-metre gap through all three banks, with a causeway carrying the old approach path across the intervening ditches.