What makes the cashel at Caherbullog quietly peculiar is not just the structure itself but the way later generations built directly on top of it, treating its ancient walls as convenient foundations for their own field boundaries, layering one era's organisation of the land onto another's without ceremony.

A cashel is a type of ringfort defined by a stone rather than an earthen enclosure wall, and this example is roughly oval in plan, measuring approximately 37.5 metres north to south and 32 metres east to west. The enclosing wall, around 1.2 metres wide, has largely collapsed, though its original inner facing is still legible on the western side. The outer face survives best at the north, where it still stands to about 1.2 metres in height, diminishing progressively around to the west. Set into the thickness of the enclosing wall at the south-west and north-north-west are what appear to be hut sites, small cellular spaces absorbed into the fabric of the perimeter rather than built separately inside it, which suggests a relatively sophisticated use of the available structure. Beneath the northern interior lies a souterrain, an underground stone-lined passage typically used in early medieval Ireland for storage or as a refuge, adding another layer to the complexity of the site. The cashel sits within an extensive field system representing multiple periods of use, and later field walls have been constructed directly on top of the outer wall-face, with others abutting the cashel's perimeter on three sides. The site was recorded on the Ordnance Survey six-inch map of 1915, by which point the cashel had already been absorbed into the working agricultural landscape around it.