It measures roughly 35 metres east to west and 33 metres north to south, and what makes it structurally interesting is its layered profile: an inner bank, a fosse (a defensive ditch), and then an outer bank beyond that. The outer bank has largely disappeared, surviving only along the eastern side, but enough of the whole arrangement remains to read the original intent.

The site is tentatively identified as a moated site, a category of medieval enclosure typically associated with the Anglo-Norman period in Ireland. Moated sites were usually the fortified homesteads of lesser landowners or free tenants, the fosse and surrounding banks providing a degree of defensible separation from the outside world. They tend to date from the thirteenth and fourteenth centuries, though not every example fits that pattern neatly. What complicates the picture at Moneen is the rectangular platform abutting the western side of the enclosure, measuring 33 metres north to south and 18 metres east to west, and defined by a low scarp rather than a full bank. Its function is unclear, though attached platforms of this kind sometimes served agricultural or domestic purposes ancillary to the main enclosure. The proximity to the mortuary chapel adds another layer of uncertainty, raising questions about whether the two monuments share any historical connection or simply occupy the same general area by coincidence.