This is a cillín, a type of unconsecrated burial ground used historically across Ireland for those who could not be interred in sanctified ground, most often unbaptised infants. The practice was rooted in the theological position that souls who died before baptism were excluded from Christian burial, and so communities established their own quiet places on the margins, often on ancient or liminal ground.

The site is known locally as Cliabh Cillín, a name that carries both the Irish word for a small church or graveyard and the particular weight that local memory attaches to such places. It measures roughly twelve metres north to south and seventeen and a half metres east to west, its northern edge defined by a low curving bank of earth and stone, with further traces of that boundary surviving to the west. Inside, numerous small stones have been set into the ground, and a roughly circular arrangement of stones sits just within the northern bank, a detail that hints at deliberate, if modest, organisation. The site was recorded in Paul Gosling's Archaeological Inventory of County Galway Vol. I, published in 1993, which remains the principal documentary source for early monuments across this part of the west.

Cilliní are found throughout Ireland, but they tend to be easy to overlook precisely because they were designed to sit apart, neither signposted nor celebrated. The stones at Lettergesh are small and uncarved, the banks low enough to be mistaken for field margins by anyone not looking carefully. That plainness is itself part of what these sites communicate about the communities that maintained them.