What the 1838 six-inch map recorded as a rectangular structure at Rathlackan in County Mayo, roughly nine metres east to west and six metres north to south, had vanished from the cartographic record entirely within less than a century. What remains today gives little away: a low square platform, barely thirty-five centimetres high, sitting near the centre of an enclosure and edged by an intermittent kerb of upright stones. Whether it represents the footprint of that earlier building, reworked or robbed out over time, is uncertain. The site is classified as a possible church, and the qualification matters.

The enclosure itself carries its own quiet weight. It served as a children's burial ground, known in Irish tradition as a cillín, a practice widespread across Ireland from the medieval period into the twentieth century. Cilliní were typically used for the burial of unbaptised infants and others considered outside the boundaries of consecrated ground, children who, under Catholic doctrine, could not be interred in the parish churchyard. They were often sited at older, liminal places, pre-Christian enclosures, ancient ringforts, or ruined ecclesiastical sites, and Rathlackan fits that pattern. The low platform at the centre, defined by its kerb of upright stones, may represent foundations that were adapted or modified in the more recent past, though the extent of any such alteration is unclear.