The site at Cahirduff sits in level pasture, just 70 metres north of the townland boundary with Monaster North, and its current form tells a story of incremental loss as much as ancient occupation. A ringfort, sometimes called a rath, was a roughly circular enclosure, typically defined by one or more earthen banks and ditches, used as a defended farmstead during the early medieval period in Ireland. Thousands survive across the country in varying states of preservation, but Cahirduff offers a particularly legible example of what happens when a monument is only partially spared.

The 1840 edition of the Ordnance Survey Ireland map recorded the site as a clearly circular enclosure. Sometime between that survey and the 1897 twenty-five-inch edition, the south-western bank was levelled, most likely to accommodate a post-1700 field boundary that cuts across that section. By the time the Archaeological Survey of Ireland examined the monument in 2007, the picture was more complicated still. Surveyors Alison McQueen and Vera Rahilly recorded a D-shaped area measuring roughly 32 metres north-west to south-east and 30 metres north-east to south-west. Its eastern arc is defined by a scarp about 3 metres wide and just over a metre high, together with an earth and stone field boundary aligned with a mature hedgerow. The western side survives only as a slight linear scarp, where another former field boundary has since been removed. An external fosse, the ditch that would originally have run around the outside of the enclosure, remains visible across the northern arc, with traces also surviving to the south-east. The interior is grass-covered but carries both a stone wall running across the north-west quadrant and a trackway, roughly 2.2 metres wide, crossing the south-east.

The site is not formally open to visitors, and as working pasture it should be approached with the usual courtesy owed to farmland. Aerial imagery taken between 2005 and 2018, including Google Earth ortho-images, shows the monument clearly as a roughly C-shaped area open to the south-west, which gives a useful sense of its current extent before visiting. A related enclosure is recorded about 300 metres to the west-south-west, so the wider landscape here carries more archaeology than a single field-walk might suggest. The monument is most legible at low sun angles, when the remaining scarps and the fosse traces cast enough shadow to read the original form beneath the grass.