The site at Lismagonway is a ringfort, the kind of enclosed settlement that was commonplace across early medieval Ireland, typically defined by one or more earthen banks and ditches and used as a farmstead or place of refuge. What survives here is a subcircular enclosure measuring approximately 34.5 metres from east-northeast to west-southwest and 30 metres across the shorter axis, still partly defined by an overgrown earthen bank and an outer fosse, the ditch dug to accompany such a bank.

The positioning just south of the drumlin summit is characteristic of how these sites were often placed: high enough for visibility and drainage, but not fully exposed on the skyline. The outer fosse appears to have been re-cut along the northern to southeastern arc at some point, suggesting the enclosure was maintained or modified over time. The southeastern to south-southwest stretch of the bank and ditch has been lost entirely, replaced by farm sheds that now occupy that portion of the perimeter. The original entrance, 2.5 metres wide at its base, was located on the southeastern side, which is also where the modern farm infrastructure has since intruded. A narrow gap in the ground is not much to look at, but an entrance width of that scale is consistent with what survives at comparable earthwork enclosures across Ulster, wide enough for livestock, small enough to control.