A cashel, the term used for a ringfort built from dry-stone walling rather than earthen banks, once occupied a slight rise above the surrounding reclaimed pastureland, its circular outline sitting among the outcropping limestone that characterises this part of Connacht. By the early 1950s, no visible surface trace of it remained.

The structure was recorded on the 1838 edition of the Ordnance Survey six-inch map, which captured it as a circular enclosure roughly forty metres in diameter. Ringforts of this kind were typically built during the early medieval period, between roughly the fifth and twelfth centuries, and served as enclosed farmsteads, their walls or banks offering protection for people, livestock, and stores. The cashel at Drumharsna would have been a modest but solid presence on that low rise, its stone walls rising above the limestone pavement. When McCaffrey surveyed the area in the early 1950s and noted its disappearance, the site had already been absorbed entirely into the working agricultural landscape around it, the stone most likely cleared or robbed out over the intervening century as pastureland was improved and field boundaries reorganised.

What remains is the cartographic ghost: a circle drawn by an Ordnance Survey mapper in 1838, careful enough to note the enclosure's presence, unknowingly making the only durable record of something that would not survive another hundred years.