What is visible amounts to a hollow filled with nettles on a south-facing slope of grassland, yet this modest depression was significant enough to be recorded on the 1838 edition of the Ordnance Survey six-inch map, which charted Ireland in extraordinary detail at a time when many such features were still legible in the landscape. The enclosure measured roughly twelve metres in diameter, placing it in the range of a small ringfort or related enclosure type, the kind of circular earthwork that was used across early medieval Ireland for settlement, storage, or ritual purposes.

The 1838 mapping gives a useful fixed point: whatever the enclosure once was, it was still recognisable as a distinct feature in the landscape at that date. At some point after that it was reduced, either by agricultural clearance or simple erosion, to the hollow that remains today. What makes the site more than an unremarkable footnote is its association with a children's burial ground. Known in Irish tradition as a cillín, such burial grounds were used for the interment of unbaptised infants and others who, under Catholic practice, could not be buried in consecrated ground. They are frequently found at the edges of ancient enclosures, ringforts, or other pre-Christian sites, places regarded as liminal or set apart, where the boundary between the everyday world and something older was felt to be thin. The pairing of enclosure and cillín at Annaghcallow follows a pattern found in many parts of the west of Ireland, though each site carries its own particular silence.