The Ordnance Survey's first edition six-inch map of 1840 marks it simply as "Grotto", with a small crescent-shaped symbol, yet by the time the surveyors returned for the revised edition of 1900 to 1905, it had been dropped from the record entirely. What was once considered significant enough to name had, within a few decades, apparently ceased to register.

The structure sits on a natural rocky ridge roughly 200 metres west of the Suir, and about 150 metres northwest of the ruins of Athassel Abbey, one of the largest Augustinian priories ever built in Ireland. Its bridge and gatehouse lie even closer, barely 50 metres to the southeast. The current working theory is that this was not a grotto in any devotional or decorative sense, but a limekiln, a stone-built furnace used to burn limestone down into quicklime for use in agriculture and construction. A limekiln built into a natural ridge would have drawn on two ready sources of material: the stone of the ridge itself, and the dressed and rubble stone of the adjacent abbey, which had been in decay since its suppression in the sixteenth century. The abbey, in other words, may have been quietly cannibalised to feed an industrial process, its medieval fabric recycled into a workaday tool of the land. That the OS cartographers chose to call the result a "Grotto" suggests either a misreading of its form or, possibly, a local name that had already obscured its original purpose by the time anyone thought to write it down.