On its north-western side, the enclosure relies on a steep ravine cut by a tributary of the Oghermong; everywhere else, it depends on a bank, a fosse, and the possible remains of an outer bank. That combination, where landscape and labour share the work of defence, gives the site an unusual character among the ringforts of the Iveragh peninsula.

A rath, to give it its Irish term, is a type of enclosed farmstead typically built between the early medieval period and around the twelfth century, defined by one or more earthen banks and accompanying ditches. This example at Gortlissaline is carefully constructed. The flat-bottomed fosse, the outer ditch, is best preserved along the northern to south-eastern arc, where it measures 3.8 metres wide. The inner bank reaches 2.4 metres above the fosse at its highest point to the south, and its inner face is reinforced with a series of upright stone slabs at that same southern stretch. An entrance gap 3.8 metres wide survives at the south-east, with some drystone masonry remaining on either side of the eroded opening, and a causeway crossing the fosse at that point to allow access. These are not incidental features; they suggest a deliberate and considered approach to construction, even if centuries of weathering have softened the whole.

The interior is uneven, scattered with loose stone, and in the north-western quadrant a low mound about 8 metres in overall diameter may represent the collapsed remains of a hut, with what appears to be an entrance facing east. It is speculative, as such things often are, but the scale is consistent with a small domestic structure of the kind associated with this type of enclosure. The ravine boundary to the north-west adds a slightly wild quality to the site; the engineered earthworks meet natural terrain in a way that makes it feel less like a monument and more like a place where someone once made practical decisions about safety, water, and the lie of the land.