The roughly circular enclosure, measuring around 31 metres north to south and 30 metres east to west, was once defined by an earthen bank and a wide, shallow fosse, the term for the ditch that typically runs outside such a bank. The bank has been levelled along its western and northern arc, and the fosse, though still traceable at about five metres wide, is shallow enough to pass almost unnoticed. A ringfort, or rath, was a farmstead type common across early medieval Ireland, in use roughly between the fifth and twelfth centuries, enclosed for the protection of livestock and household rather than as any kind of fortification in the military sense. This one sits on low-lying pasture close to boggy ground, with bog recorded just 90 metres to the north and 130 metres to the west, a landscape that would have required careful management of water and soil.

Inside the enclosure, the ground slopes gently from northwest to southeast, and faint cultivation ridges are still visible crossing the interior. These ridges suggest that at some point the enclosed area was worked as tillage ground, a use that would gradually have worn down whatever internal features the original settlement left behind. A number of banks and depressions in the surrounding area are thought to be drainage features, reflecting the ongoing effort to make productive land of a naturally wet and marginal terrain. A second ringfort sits just 140 metres to the southeast, which is not unusual; paired or clustered raths appear across the Irish midlands, sometimes associated with related family groups farming adjacent land. The Cappagh site lies 120 metres east of a stream feeding into the Inny River, a watercourse that winds through County Westmeath and has marked the boundaries of settlements in this region for centuries. By 2011, the monument was entirely surrounded by a forestry plantation, which may have protected what remains from further agricultural disturbance while making it considerably harder to see.