What makes this particular cashel quietly remarkable is not so much its own condition, which is partial and much reduced, but its position within a cluster of similar monuments so dense that three other cashels or enclosures lie within 160 metres of it in various directions. This is not an isolated farmstead from early medieval Ireland but something more like a neighbourhood, each enclosure a node in a field system that has accumulated layers of use over a very long period.

A cashel is a stone-walled ringfort, the equivalent in rocky upland terrain of the earthen raths found elsewhere in Ireland. They were typically built and occupied during the early medieval period, roughly the fifth to twelfth centuries, serving as enclosed farmsteads for families of some local standing. The Teergonean example is subcircular, measuring roughly 23.75 metres east to west and 20.5 metres north to south internally. Its defining wall was originally double-faced, meaning it had a dressed stone face on both its inner and outer sides, a construction method that implies some care and resource in the building. The wall survives best at the north-north-west, where the outer face still stands to around 35 centimetres, but around the north it has been reduced to a stony scarp, and from the north-north-east around to the east-south-east it has collapsed into a spread bank up to five metres wide. At the east-south-east the wall appears to have been built wider, possibly with a double outer face, to compensate for the steeply sloping ground on that side. The interior is slightly dished and slopes eastward. A souterrain, an underground stone-lined passage used for storage or refuge, lies within the enclosed area, adding another layer of function and period to the site. A later field wall has since cut across the north-west quadrant, absorbing part of the cashel's interior into a more recent agricultural arrangement. The monument was already recorded on the Ordnance Survey 25-inch plan of 1897 and appears again on the 1920 edition of the six-inch map, though it was catalogued in 1996 simply as an enclosure, a designation that undersells both its structure and its context.