Perched beside the Cummeragh river on the Iveragh Peninsula in County Kerry, with the river dropping south into Lough Currane nearby, the site occupies ground where any miscalculation in its construction, or any serious erosion over the intervening centuries, might have seen it disappear entirely. That it survives in reasonable shape on its outer face makes it worth a second look.

A caher, sometimes spelled cahir, is the Irish term for a stone ringfort, a type of roughly circular enclosure built during the early medieval period and used primarily as a defended farmstead or the residence of a local chieftain. The Lislonane example is a substantial one, measuring about 26.8 metres across internally on its north-south axis and 25 metres east to west. Its enclosing wall is built in drystone masonry, a technique that uses no mortar, with a rubble and earth core faced on both sides with carefully laid stone. The external face has survived well, rising to an average of 3 metres in height and built with a slight batter, meaning the wall leans inward very gently at its base, a feature that adds stability. The internal facing has largely collapsed, leaving a maximum interior height of only 1.1 metres. A 2.6-metre entrance gap opens to the south, and the interior itself is flat and clear of any visible features. The site was recorded and described by A. O'Sullivan and J. Sheehan in their archaeological survey of the Iveragh Peninsula, published by Cork University Press in 1996.