A cashel is simply a ringfort built from stone rather than earth and timber, the preferred construction method in rocky regions like the Burren and its fringes, where limestone lies close to the surface and rubble is easier to gather than soil is to bank. These enclosures, typically dating from roughly the fifth to the twelfth centuries, served as farmsteads for local farming families, their circular walls defining a domestic world of houses, animals, and small-scale agriculture rather than anything we might recognise as a fortress in a military sense.

Clare is unusually rich in such monuments, and Poulbaun sits within a county where the cashel form is almost a signature feature of the early medieval countryside. The circular or oval enclosure, its walls sometimes still standing to a considerable height in better-preserved examples, would originally have enclosed a family's living quarters and protected their livestock from wolves and opportunistic raiders. In the townland of Poulbaun, the specific dimensions, ownership history, and current condition of this particular cashel remain difficult to pin down with precision, as detailed records have yet to be made widely available. What is not in doubt is that the monument exists as a registered site, recognised within the national inventory of archaeological monuments, and that its presence in this corner of Clare adds to a broader pattern of early medieval settlement that shaped the land long before any surviving documentary record.