The structure is a cashel, the Irish term for a ringfort built from dry-stone walling rather than earthen banks, and this one retains the remains of a double-faced stone wall that traces a subrectangular plan, running roughly 28 metres on its north-east to south-west axis and 24 metres from north-west to south-east. The double-faced construction, where two lines of upright stonework sandwich a rubble core, was a common technique for achieving the necessary mass and stability in these enclosures, which typically served as farmsteads during the early medieval period.

The site is recorded within a wider field system on the slopes of Slieve Elva, the karst upland that forms part of the Burren's northern edge, and its eastern portion was already noted on the Ordnance Survey six-inch map of 1915, suggesting the remains were sufficiently visible at that date to catch a surveyor's attention. The name Caherbullog carries the word caher, an anglicisation of the Irish cathair, itself another term for a stone-built enclosure of this type, which hints that local memory of the structure's character persisted long enough to attach itself to the place-name. Cashels of this kind are scattered across the limestone landscapes of Clare and Galway, but many are now so reduced by field clearance and stone robbing that only aerial or ortho photography reveals their former extent with any clarity.