What survives today is technically penannular, meaning it forms an almost-complete ring rather than a closed one, open to the south-east and fringed by trees that make it legible from the air even when it is hard to read at ground level. Unusually, it sits within about eighty metres of a second ringfort, the two monuments occupying the same ridge together, which raises questions about how such sites clustered and what that proximity once meant.

A ringfort, known in Irish as a rath, was typically a circular or oval enclosed settlement, built from the early medieval period onwards and used for farming households or, in some cases, for livestock. The Calliaghstown example measures roughly 33 metres east to west and 27.5 metres north to south, and its enclosure is more complex than the term "ringfort" might suggest: there is an inner bank, a flat fosse or ditch between it and a berm-like feature, a counterscarp bank beyond that, and an outer scarp that may originally have been an old field boundary. By 1980, when the site was described in detail, much of this layering had been reduced or levelled, particularly along the southern arc. The northern portion of the inner bank remains comparatively steep and clear. A gap of about 4.5 metres at the top of the bank on the northern side is the result of modern disturbance rather than an original entrance. Comparing the 1837 Ordnance Survey six-inch map, which shows a complete circular earthwork within a small square field, with the revised 1913 twenty-five-inch edition, which already shows the open penannular form, suggests that significant degradation had occurred in the intervening decades, likely through agricultural activity gradually encroaching from the south-east.