What appears today as a roughly D-shaped area defined by a collapsed drystone wall was recorded on the 1838 edition of the Ordnance Survey six-inch map as a more rounded, subcircular form, measuring approximately 28 metres east to west and 25 metres north to south. The discrepancy between those two shapes is part of what makes the site worth pausing over. The surviving drystone wall, about 75 centimetres wide in places though fallen in others, may simply be following the curve of something far older beneath it.

The site is classified as a cashel, which is a type of ringfort enclosed by a stone wall rather than an earthen bank. Ringforts were the dominant settlement form of early medieval Ireland, typically serving as farmsteads for a single family and their livestock, and cashels are their stone-built equivalents, more common in areas where building stone was readily available. What complicates the picture at Cahercon is the presence of a children's burial ground within the enclosure's interior. These sites, known in Irish as cillíní, were used to inter unbaptised infants and others who, under Catholic practice, could not be buried in consecrated ground. They are found across Ireland in considerable numbers, often reusing prehistoric or early medieval enclosures, and their presence here suggests the cashel served as a quietly significant place well beyond whatever domestic function it may once have held. The straight northern side, 25 metres long, gives the enclosure its current D-shape and may reflect either later modification or the partial survival of the original outline.