This is a rath, the Irish term for a ringfort, the enclosed farmstead type that was built in enormous numbers across Ireland during the early medieval period, roughly between the fifth and twelfth centuries. Most were the homes of farming families of middling status, enclosed by an earthen bank and a surrounding ditch, called a fosse, for reasons that were as much about social display as physical defence. The Balrowan example is modest even by those standards, measuring roughly 22 metres on its longest axis, oval rather than perfectly round, and only partially intact.

When the site was formally described in 1970, surveyors found that the earth and stone bank survived reasonably well along the southern and western arc, but had been reduced to a mere scarp along the north-eastern side, where the ground simply drops away into the interior rather than rising and falling as a proper bank should. The outer fosse, the shallow ditch that would have reinforced the enclosure, was only faintly visible along the southern and western stretches. A gap in the bank at the south-south-east, about four metres wide at the top and narrowing to less than two metres at the base, is thought to mark the original entrance. A larger, less orderly break at the north-west is almost certainly later disturbance rather than any intended feature. Inside, the ground slopes gently toward the north-north-east, and traces of cultivation ridges run across it from west-north-west to east-south-east, suggesting the interior was worked as farmland at some point after the enclosure fell out of use. The monument appeared on the revised 1913 Ordnance Survey 25-inch map as an oval earthwork, and aerial photography shows it still partially outlined by trees.