It is nearly two metres thick, its top blurred by grass and low vegetation, and it encloses a roughly oval space measuring about 42 metres north to south and 39 metres east to west. The interior is uneven underfoot. There is nothing dramatic about the way it sits in the landscape, and that is partly what makes it arresting: a solidly built enclosure, clearly the product of considerable effort, quietly occupying a slight raised area as it has done for well over a thousand years.

This is a cashel, the term used for a ringfort, of which there are thousands across Ireland, built using stone rather than earthen banks. Ringforts were the basic unit of rural settlement in early medieval Ireland, typically enclosing a farmstead and its outbuildings, offering some protection for livestock against raid and predator. The cashel form is particularly common in areas where stone lay readily to hand. The name Cahernagry preserves the Irish word cathair, another term for a stone ringfort, so the landscape here has been quietly announcing what it contains for centuries, in the place name itself. The wall at this site, nearly two metres high and almost as wide, represents a substantial construction, suggesting a household of some standing within the local community of its time.