The exact building is gone, or at least unidentified, and the street has changed beyond recognition over four centuries, yet the record of what happened there survives with a precise, almost startling clarity: a chamber over the premises of one Charles Carroll, victualler, serving as a place of Catholic worship at a time when such arrangements were both necessary and dangerous.

The detail comes from a diocesan survey compiled early in 1630 by Bulkeley, the Church of Ireland Archbishop of Dublin, who drew up a report cataloguing the Mass-houses then operating across the diocese. His purpose was surveillance rather than preservation, but the document he produced ended up recording something valuable. As quoted by Nicholas Donnelly in his 1904 study of Roman Catholic chapels in Dublin, the survey notes that the chapels of St. Catherine and St. James were both located in a chamber situated over Carroll's house. A mass-house was not a formal church but rather an improvised space, often a room in a private dwelling, where Catholic worship could be conducted under the legal and social pressures of the Penal era. Using a commercial premises as cover, tucking a chapel above a working butcher's shop, was a practical solution to a precarious situation. The fact that two separate parish congregations, St. Catherine's and St. James's, shared the one room adds a further layer of texture to the picture.

Thomas Street still exists, running westward from the old heart of the Liberties, and it remains a busy working street with deep roots in Dublin's commercial and craft history. No physical trace of Carroll's premises has been identified, and there is no marker or monument to indicate where the chamber once stood. For anyone walking the street today, the interest lies less in finding a specific spot and more in reading the street itself as a document, knowing that somewhere along its length, above the noise of a butcher's trade, people gathered quietly for worship in the early decades of the seventeenth century.