A ringfort, to use the general term, is a roughly circular enclosure defined by one or more earthen or stone banks, widespread across early medieval Ireland and most commonly associated with farmsteads. What makes Lisderg worth a second look is the density of structures within its interior, and the variety of their forms.

The enclosure itself is defined by an earthen bank 5.5 metres wide, rising 1.6 metres on its outer face and about 0.9 metres above the interior floor, which sits at roughly the same level as the surrounding land. Within that circuit, the four house-sites present a range of shapes and scales. The largest, positioned to the south-east, is sub-rectangular and measures approximately 8 metres by 7.4 metres externally, with walls around a metre thick. To the west, a sub-semi-circular enclosure curves inward against the bank, and a short distance to its north sits a small rectangular structure, roughly 4.2 metres by 3.5 metres externally, with walls 0.6 metres thick. Loose stones elsewhere in the interior suggest further features that have not fully survived. The site sits south-east of St Mary's Roman Catholic Church and commands good views in all directions, a positioning that was rarely accidental in the landscape choices of early settlement. The description of these structures was recorded by C. Toal in the North Kerry Archaeological Survey, published in 1995.