This is a rath, the most common type of ringfort in Ireland, built as an enclosed farmstead during the early medieval period, roughly between the fifth and twelfth centuries. What makes the example at Knockbweeheen worth attention is the completeness of its concentric design and the sheer scale of what survives, even as gorse and dense overgrowth steadily reclaim it from the outside in.

The site was recorded and compiled by Denis Power, with notes uploaded in August 2011. The circular interior measures 34.5 metres on a north-south axis and is enclosed by two earthen banks separated by a fosse, the term for the ditch dug to create the bank material. The inner bank rises to an external height of 3.4 metres, which is considerable for an earthwork of this kind, while the outer bank reaches 2.05 metres on its interior face. Between the two banks, a wide intervening fosse stretches to 4.2 metres across. A further outer fosse, shallower and narrower, is visible to the south and south-east. There are two breaks in the outer bank, one to the ENE at roughly two metres wide, and a much broader gap of eight metres to the south, which likely marks the original entrance. Field boundaries that once abutted the site to the north-west, north-east, and south, as recorded on the 1923 Ordnance Survey six-inch map, have since been levelled, leaving the ringfort standing in relative isolation.

The level interior is under pasture, and the hill position gives genuinely wide views of the surrounding landscape, which would have been a practical consideration for whoever originally chose the site. The disused quarry immediately to the east and a coniferous plantation about fifty metres to the west are the main modern intrusions. The dense overgrowth covering much of the outer bank and the fosse between south-south-west and east makes a full circuit of the earthworks difficult on foot, though the section from east to south-south-west on the outer bank remains clearer. Visitors approaching from the south will find the wide entrance gap the most readable feature, giving a reasonable sense of how the enclosure was originally structured.