That detail alone says something about the quiet rate at which places like this are slowly edited by time. The ruined church at Kilcloony sits at the base of a ridge near the western edge of Ballinasloe, roughly 150 metres south of the Deerpark River, enclosed within a rectangular graveyard that still functions as the site's most visible boundary.

The remains standing today are those of a medieval parish church, oriented east to west and measuring approximately 15 metres long by 5 metres wide, described as being in fair condition. Its surviving architectural details reward a close look. The south wall contains a pointed arch doorway and a round-headed window, while the east gable holds an ogee-headed window, a late medieval decorative form in which the arch curves outward before curving inward to a point, giving a slightly sinuous profile. The west gable once contained a very small window, noted in the Ordnance Survey Letters compiled by O'Flanagan in 1927, but no trace of it remains. Underneath the medieval fabric, tradition places something older still. The site was long regarded as the location of the Early Christian church of Saint Grellan, a figure associated with the Uí Maine, the powerful Connacht dynasty whose territories centred on this part of east Galway. Early Christian churches in Ireland were typically modest timber or stone structures, often later rebuilt in the Romanesque or Gothic styles visible in surviving ruins today, which is the likely sequence here too.