The site at Knockalinsky, set on a rise above pasture in County Mayo, is a little different. Here, two roughly oval enclosures sit side by side, their banks meeting at shared north and south points, giving the whole complex a double-lobed shape that is considerably less common than the standard single-ring rath.

A rath is an earthen ringfort, typically dating from the early medieval period, roughly 500 to 1000 AD, and used as a defended farmstead. At Knockalinsky, the northern enclosure measures approximately 50 metres north to south and 41 metres east to west; the southern one is similar in scale at 46 by 43 metres. Both are enclosed by earthen banks into which large boulders have been incorporated, and heavy vegetation has grown over them across the centuries. The southern enclosure retains an external fosse, a defensive ditch, as well as an outer bank running from the north-east to the west of that enclosure, suggesting the southern ring was considered the more exposed or more important of the two. Within the northern enclosure, there is a possible souterrain, an underground stone-lined passage or chamber of the kind often associated with Irish ringforts, used variously for storage, refuge, or ventilation of a dairy. Whether it is a true souterrain or a natural feature of the ground has not been confirmed.

The boulders folded into the banks are a detail worth pausing over. In a region where glacial erratics are common, incorporating large stones into earthwork construction was both practical and labour-saving, but it also gives the overgrown banks at Knockalinsky a slightly rougher, more massive quality than earthen raths elsewhere. The whole site sits quietly in farmland, its paired enclosures softened by time and growth, the fosse still just legible in the ground.