This is not a ruin you can visit or a plaque you can photograph; it is an absence, a gap in the streetscape where something furtive and significant once happened. The mass-house, as such spaces were known, was not a purpose-built church but typically a private dwelling or room within one, pressed into service for worship at a time when Catholic practice was officially suppressed. That these places existed openly enough to appear on a government surveillance list is one of the stranger ironies of early seventeenth-century Dublin.

The earliest documentary evidence comes from a 1618 Government list of Catholic clergy, which noted the places of most public note where priests were known to gather for Mass in Dublin. Three addresses on High Street appear by name: a back room in the house of Nicholas Queitrot, a back room belonging to someone recorded only as Cary, and a back room in the home of Widow O'Hagan. The list, as historian N. Donnelly noted in his 1904 study of Catholic chapels in Dublin, was an incomplete one, compiled by authorities more interested in surveillance than in preservation. By 1630, the Church of Ireland Archbishop Bulkeley had drawn up a fuller report of mass-houses across the diocese. One entry recorded a chapel serving St. Michael's parish, situated at the rear of Mr. George Taylor's house, in the space between High Street and Back Lane. None of these locations has been precisely identified on the modern streetscape, and the buildings themselves are long gone.

High Street today is a busy stretch of the old medieval city, running roughly westward from Christchurch Cathedral. There is nothing to mark where these rooms once served their quiet, careful purpose, and that is rather the point. A visitor interested in this history might find it useful to read Colm Lennon's work on Dublin in the age of the Reformation alongside Donnelly's survey, both of which give texture to what the bare addresses imply. The area around Back Lane, which still exists as a street, offers at least a sense of the tight urban geography in which these arrangements operated, houses backing onto laneways, rooms accessible from the rear, the whole arrangement suited to discretion.