It is not an especially dramatic ruin, and there is no visible entrance to betray how people once moved in and out of it. What remains is an earth and stone bank, partially disturbed along its south-western and western sides, and a shallow external fosse, a defensive ditch dug around the outside of the bank, still faintly legible along the northern edge. The dimensions recorded across two separate surveys, in 1971 and 1978, give the enclosure as approximately 27.3 metres on its north-north-west to south-south-east axis and 26 metres east-north-east to west-south-west, making it a modest but respectable example of its type.

This is a rath, the Irish term for a ringfort, the most common archaeological monument in the Irish landscape. Ringforts were typically enclosed farmsteads of the early medieval period, their banks serving as boundaries and as a degree of protection for the family, livestock, and structures within. The Ardnagragh example adds one detail that lifts it slightly out of the ordinary: within its eastern quadrant, on a slope that faces south-east, there is a possible souterrain. A souterrain is an underground passage or chamber, usually stone-lined, associated with early medieval settlement sites in Ireland. They are thought to have served various purposes, including storage and, in some circumstances, refuge. The one here has not been excavated or fully confirmed, but its presence as a candidate feature gives the site a subterranean dimension that the surface alone does not suggest. The hilltop position, chosen presumably for visibility and command of the surrounding land, would have made this a well-situated homestead for whoever built and occupied it.