A fulacht fia recorded at Ballylin in County Limerick belongs to this category. These sites, found across Ireland in their thousands, are generally understood to be prehistoric cooking places, where stones were heated in fire and dropped into water-filled troughs to bring them to the boil. They typically survive as horseshoe-shaped mounds of burnt and shattered stone, often in low-lying or wet ground. The Ballylin example, however, presents a more ambiguous picture.

When researchers from University College Cork investigated the site during the 1980s, they found no visible surface trace of a fulacht fiadh. The ground in question is described as uncultivated, densely overgrown with trees, bushes, and briars, and situated on a sharp south-east-facing slope. That combination of factors is telling. The heavy vegetation could certainly conceal surviving earthworks, but a steep slope is an unusual setting for this type of monument, which more commonly occupies level or gently undulating terrain near water. Whether the site was originally misidentified, has eroded away entirely, or simply lies buried beneath decades of unchecked growth, the record compiled by Denis Power does not resolve. The entry was uploaded in August 2011, preserving the uncertainty rather than papering over it.

For anyone curious enough to seek it out, the practical reality is that access would be genuinely difficult. Dense briar and scrub on a steep slope makes for slow and uncomfortable going, and there is nothing guaranteed to reward the effort in the form of a visible feature. The value of a visit here is less about what can be seen and more about what the absence of evidence prompts you to consider: how many sites in the Irish record exist in this state of documented uncertainty, known mainly because someone once thought something might be there, and noted down that, on inspection, it was not.