It marks an Anabaptist meeting house, a congregation whose presence in this corner of the Liberties predates even that map by more than a century. The alley is now called Swift's Alley, and the building it once sheltered is long gone, but the cartographic record preserves something easy to overlook: that one of the most theologically radical forms of Protestant dissent in early modern Europe had quietly established itself here, just inside the parish of St Nicholas Without, immediately east of the boundary with St Catherine's parish.

The Baptists, who practise adult baptism by full immersion rather than infant baptism, a distinction that made them deeply controversial in both Catholic and mainstream Protestant eyes, arrived in Dublin around 1650, during the upheaval of the Cromwellian period. According to the scholar Crawford Gribben, it was the Reverend Thomas Patient, a preacher associated with Dublin Cathedral, who established the first Baptist meeting house in Ireland on this very site in 1653. Writing in 1831, Francis Hardy noted that a replacement building was erected in 1738 on the footprint of the original, and that by his time the congregation, though meeting in a large house, had declined considerably. By 1835, the building had been converted to use as a free church, a general term for a congregation independent of any established denominational structure.

Swift's Alley runs between the Coombe and Francis Street in Dublin's south city, a neighbourhood still dense with early street patterns despite generations of redevelopment. The meeting house itself no longer stands, but Rocque's 1757 map, which is freely accessible through the Bibliothèque nationale de France's digital archive at Gallica, allows anyone to locate its precise position relative to the old parish boundary. That boundary, shown as a red line on the eighteenth-century map, can still be traced on the historic Ordnance Survey Ireland maps available through the OSi's online portal, giving the site a faint but legible outline in the modern streetscape. It is the kind of place best approached with a map in hand, old and new layered together.