This is a rath, the most common form of early medieval enclosure in Ireland, typically built as a defended farmstead by a family of some local standing. What makes the example at Corbetstown particularly interesting is not any single dramatic feature, but the degree to which its structure has survived and can still be read on the ground.

The fort was noted on the 1837 Ordnance Survey Fair Plan map under the name 'Corbetstown Fort', which at least fixes its recognition as a landmark well into the nineteenth century. When the monument was described in detail in 1970, it measured roughly 35 metres in diameter, enclosed by two earthen banks with an intervening fosse, the term for the ditch dug between or around defensive earthworks. The inner bank remained steep on its exterior face, though it had been reduced in places to little more than a scarp. The outer bank survives from the south-east around to the west-northwest, though a road has cut through it on the western side, erasing any trace of the original entrance. Within the interior, a large circular depression in the north-west quadrant and several smaller ones hint at structures or pits that once served whoever lived here. A small excavation in 1978 exposed what appeared to be an old habitation layer, with fragments of animal bone and flecks of charcoal suggesting the residue of domestic life, cooking fires and livestock kept close by.

Situated at 112 metres above sea level, the site commands clear views in every direction across the surrounding pasture and tillage, a reminder that the choice of even a modest elevation was rarely accidental. From aerial photography the fort is now most visible as a roughly circular tree-lined earthwork, the vegetation that has colonised its banks outlining a shape that the ground alone might no longer make obvious to a passing eye.