Sometime before 1842, when the Ordnance Survey first mapped this part of Mid Cork at the six-inch scale, someone had incorporated a kiln for burning limestone into the western earthwork of what was already a very old enclosure. A lime kiln is a simple industrial structure, typically a stone-lined pit or furnace used to convert limestone into quicklime for agricultural spreading or mortar, and the fact that one was built directly into this ringfort's bank tells you something about how the site was regarded by then: as a convenient source of ready-made stonework, rather than as anything to be preserved.

The ringfort itself, known in Irish archaeology as a rath, is a type of enclosed farmstead characteristic of early medieval Ireland, roughly the fifth to twelfth centuries. Occupants would have lived and farmed within a circular earthen bank, and at Ballymorisheen the enclosure was originally bivallate, meaning it had two concentric banks rather than one. By 1904 the Ordnance Survey was still depicting it as a hachured circular enclosure roughly fifty metres in diameter, but the site has since been levelled. What survives today is a shallow circular platform, measuring approximately 55.5 metres north to south and 53 metres east to west, with a low rise reaching no more than 1.2 metres on the northern, eastern, and southern sides. The external fosse, the defensive ditch that once ran outside the bank, is still faintly legible as a shallow depression to the north and south-west, most visible where it meets a field boundary on the western side. A low rise beyond the fosse to the north may represent a counterscarp, the outer edge of that ditch, or possibly the remnant of the second bank that once made this a double-ringed enclosure.