Founded around 1210 by the Arroasian Canons of the Order of St Augustine, the priory has a fascinating origin story; it became home to the monks of Skellig Michael who abandoned their precipitous island monastery sometime before the mid-eleventh century. The treacherous conditions on that famous Atlantic rock had finally proved too much, yet the relocated community maintained both ownership of their former home and its prestigious alias, 'de Rupe Michaelis' (of Michael's Rock).

The priory buildings showcase architectural features spanning three centuries, from the thirteenth to the fifteenth, telling a story of continuous occupation and adaptation. Whilst much of the complex survives, the fate of its associated castle, located 13 metres southwest of the refectory, offers a sobering reminder of how quickly historic structures can disappear. Known locally as Caisleán Beag, this defensive structure was still relatively intact in 1841, with detailed records describing its battered archways and narrow windows. By 1900, however, only the northwest wall remained standing, and today visitors will find just fragments; the northwest wall with its ground floor rectangular opening set in a square, lintelled embrasure, and a portion of the southwest wall, now incorporated into the graveyard boundary.

Archaeological surveys have meticulously documented what remains, noting walls averaging 1.2 metres thick and internal measurements that hint at the castle's modest but sturdy construction. The 1841 Ordnance Survey Letters provide tantalising details of what has been lost, including additional walls measuring over 5 metres in length and architectural features like the 'battered archway' that once graced both the southwest and northeast walls. These remnants, though fragmentary, offer visitors a chance to trace the outlines of medieval life at this important religious site, where the monks who once clung to Skellig Michael's steep slopes found a gentler, though perhaps less spiritually dramatic, home.