A cashel is a ringfort built entirely in stone rather than earthen banks and ditches, and this one at Bellafarney is a particularly well-preserved example. What makes it quietly unusual is not just its position or its survival, but the detail concealed within its own walls: a small subrectangular chamber, roughly 1.75 metres by 1.5 metres, built directly into the thickness of the enclosing wall at the southwest. It is entered through a gap barely a metre wide, and it sits there, purposeful and discreet, in a wall that is itself up to 2.5 metres thick.

The cashel encloses a raised circular area measuring approximately 21.5 metres north to south and 18.85 metres east to west, ringed by a drystone wall whose interior face rises between 1.75 and 2 metres, and whose exterior face stands slightly higher, between 2 and 2.5 metres. The single entrance, at the south, is notably narrow at just half a metre across, wide enough for a person but not much more. Drystone construction of this kind, fitted without mortar, demands considerable skill and patience, and the wall has been repaired in places in relatively modern times, suggesting it remained useful to local farming communities long after its original inhabitants were gone. Extending outward from the cashel wall at the south and west, massive linear field walls run across the landscape, drystone-built like the cashel itself, indicating that whatever settlement this structure once anchored had an organised agricultural presence around it.