The site at Drombeg is a rath, the Irish term for a ringfort, the most common type of early medieval settlement monument found across Ireland. Most were built and occupied roughly between the fifth and twelfth centuries, serving as enclosed farmsteads for a single family or household. This one is univallate, meaning it has a single enclosing bank rather than the two or three concentric rings seen at higher-status sites.

The enclosing bank here is broad rather than tall, running to around ten metres in width while rising only 1.4 metres at its highest point on the external face and somewhat less on the interior side. The internal space it defines is nearly circular, measuring 33 metres north to south and 32 metres east to west, a diameter consistent with a modest but functional farmstead enclosure. To the south-east and east, a faint fosse, the shallow ditch that would originally have been dug to provide material for the bank, remains just legible in the ground. It survives for around 23 metres of its arc, roughly two metres wide and half a metre deep, worn down by centuries of agricultural activity but not entirely erased. The fact that the site occupies a corner of a field in poor pastureland is itself telling; land that was never deemed worth ploughing intensively often preserves earthworks that more productive ground long ago destroyed.