This is Bullán Mhaolodhair, a holy well in the townland of Cill Mhuirbhigh, though the water here is less a spring or pool than a cavity worn into the karst limestone itself. The offerings left nearby confirm that people still regard it as a living place of devotion, not a relic.

The site lies roughly 0.6 kilometres north-west of the village of Cill Mhuirbhigh, on the bare pavement that characterises so much of Inis Mór's interior. A bullán is a cup-shaped hollow ground into rock, often associated in Irish tradition with early Christian saints and with curative or ritual use; whether this particular cavity is natural or worked is not entirely clear, but it has long carried the name of a person, Maolodhair, who is otherwise unrecorded in the surviving sources. The cairn built over it, oval in plan at 2.3 metres by 1.4 metres and roughly 0.7 metres high, is a drystone structure, meaning it is assembled without mortar, relying on the careful fitting of limestone slabs. Antiquarians T. J. Westropp and M. C. O'Flanagan both noted the site in the late nineteenth and early twentieth centuries, suggesting it was already recognised as something worth recording even then.