It is the kind of origin story that says a great deal about the circumstances of Catholic worship in early eighteenth-century Ireland, when purpose-built churches were not an option and a converted outbuilding had to suffice.

The chapel appears on John Rocque's detailed map of Dublin, dated 1757, marked with a small cross symbol and shown as a rectangular structure orientated east to west, sitting to the north of Arran Quay in the parish of St. Michan's. Access was awkward by design or necessity: one laneway led from Arran Quay, a second ran off the west side of Church Street. The historian O'Hanlon, writing in 1873, noted that around 1708 the congregation had taken an old stable to the rear of what were later numbered 11 and 12 Arran Quay and converted it into a Mass house, a term used for informal Catholic places of worship during the Penal Law era, when open Catholic worship was legally restricted. The building grew inadequate as the congregation grew, and by 1785 the original structure had become sufficiently ruinous that it was taken down and rebuilt, at which point a more formal entrance was created from Arran Quay, running through a passage beneath No. 12. That arrangement still did not last; by 1835 the congregation had outgrown the site entirely and moved to a more prominent location.

There is nothing to see at the site today in any conventional sense. The car park at Arran Square occupies the ground, and nothing marks what stood there. The value is almost entirely in the mapping. Rocque's 1757 survey of Dublin, which is available to view through the Bibliothèque nationale de France's online Gallica archive, shows the chapel in enough detail to trace its footprint and its laneways relative to the quay and Church Street. For anyone walking that part of the north quays, the exercise of comparing the current streetscape with Rocque's grid is its own reward, revealing just how much of the fabric of early Georgian Dublin has quietly disappeared.