Sitting on a gentle rise in wet, undulating pasture, it presents itself today as a circle of trees visible from the air, a neat ring of growth betraying the earthworks beneath. That kind of aerial signature is common enough across Ireland's midlands, but get closer and the archaeology begins to speak more precisely.

A ringfort, or rath, is an enclosed farmstead of the early medieval period, typically defined by one or more banks and ditches surrounding a domestic interior. This one at Ballyglass measures roughly 36 metres in diameter and is defended by a substantial bank of earth and stone, a fosse (the encircling ditch), and the remains of a counterscarp, which is the outer bank thrown up on the far side of the ditch to reinforce the defensive profile. What distinguishes this example is how well the internal stone facing of the inner bank has survived, a feature not always legible in earthen ringforts that have suffered centuries of slippage and ploughing. Surveyors describing the site in 1970 and 1977 noted that the fosse is shallow but fairly wide, especially on the north-north-west and south-south-east sides, and that a gap on the north-east, some 6.4 metres wide at the top and narrowing to 2.9 metres at the base, likely marks the original entrance. Inside, near the centre of the enclosure, lies the footprint of a rectangular house site, with traces of pits and hollows nearby that may point to later quarrying activity. A stone-built internal division, attached to the inner face of the bank on the northern side of the house site, hints at the organisation of space within what was once somebody's home and working enclosure. Two further monuments lie within 200 metres to the north and north-east, suggesting this corner of Westmeath was more densely settled in the early medieval period than its quiet pasture now implies. The site was already recorded as a circular enclosure on the Ordnance Survey six-inch map of 1837, and again on the revised twenty-five-inch edition of 1913.