At Oughtdarra in County Clare, a megalithic structure once documented inside a cashel, a roughly circular stone enclosure of early medieval origin, had entirely vanished by the time archaeologists came to look for it in 1998. No trace of it remained. What was left was a loose alignment of stones running north-east to south-west, and even that was considered of uncertain age.

The structure had been recorded in some detail by the antiquarian Thomas Johnson Westropp, who visited and wrote about it in 1905. Westropp described it as sitting in the bottom of a hollow within the cashel, and gave it the local name 'Tuam', which he also rendered in a plan of the site. His account is precise enough to be tantalising: a near-square enclosure formed by north-facing slabs with a gap between them, a large block on each side, and four stones arranged in a row to the south. The internal space measured six feet eight inches from north to south, though he noted the sides were already disturbed at the time of his visit. He referred to the feature as a 'giant's grave', a term commonly applied in Irish folklore to ancient megalithic remains whose original purpose had long been forgotten by local communities. Whether the structure was genuinely prehistoric or already a ruin misread by tradition, Westropp's plan at least fixes its position inside the cashel wall.

By 1998, even the hollow Westropp described could only tentatively be identified, with a natural depression in the north-west part of the cashel thought to be the most likely candidate for the spot he marked. A separate enclosure lies roughly 85 metres to the south-south-east, suggesting the area was once more densely occupied than what remains visible today would indicate.