The enclosure at Balreagh is modest by any measure, roughly 28 metres across at its widest point, but its quiet geometry still holds. A low earthen bank, standing no more than 75 centimetres at its best-preserved stretch along the north and north-east, traces a sub-circular boundary around the interior, with a narrow entrance gap of about 1.6 metres breaking the line to the east. Outside the bank, a shallow external fosse, a drainage ditch that also served as a source of earth for the bank itself, completes the enclosure in the manner typical of a rath, the Irish term for this class of earthwork farmstead.

Raths were the most common form of rural settlement in early medieval Ireland, built and occupied roughly between the fifth and twelfth centuries, though dating any individual example without excavation is difficult. Inside the Balreagh enclosure, two features suggest something of what once went on here. Faint traces of cultivation ridges running east to west across the interior point to agricultural use at some stage, and an oval-shaped depression near the centre may be the remains of a hut site, the hollow left when a timber or wattle structure eventually decayed back into the ground. The position of the enclosure, set on rising ground with open views in all directions, is characteristic; this kind of site was rarely placed by accident, and the long sightlines across Westmeath's low pastoral landscape would have had practical as much as aesthetic value.

The earthworks sit in grassland, and the low profile of the bank means the site reads most clearly from a slight distance or in low-angled light, when the fosse and ridges cast enough shadow to resolve as distinct features. The entrance gap to the east is narrow enough to be easy to miss at first, but once located it gives the clearest sense of the original shape of the place.