Its location has never been identified, and no physical trace has been confirmed. What survives instead is a paper trail through two seventeenth-century documents, each describing a building that seems to have served as an unlikely refuge for Catholic worship during a period when such arrangements carried considerable risk.

The first mention comes from 1630, when Dr. Bulkeley, the Protestant Archbishop of Dublin, conducted a visitation of his diocese and made note of what he found in Garristown. The parish church was ruinous, he recorded, and in its place the local Catholics were gathering in what he called a great void house, nine couples long, meaning a structure spanning nine roof-rafter bays, covered with thatch. A vicar named John Mooney was attached to the place. The tone of the entry is matter-of-fact, the observation of an administrator cataloguing the state of his territory, but the detail it preserves is striking. Twenty-odd years later, the 1654 to 1656 Civil Survey of Dublin recorded a similar building on the same townland, described as a thatched stone house on the lands of Elizabeth Talbot of Malahide, an English Papist, and referred to plainly as the College of Garristown. Whether these two entries describe the same structure is not certain, but the possibility is strong enough that historians have connected them. The word college here most likely carried the older sense of a collegiate or communal establishment, perhaps with some educational or clerical function, rather than anything resembling a formal institution of learning.

Garristown is a small village in north County Dublin, and the ruined medieval church referenced in Bulkeley's visitation, recorded in the archaeological survey as DU003-011001, still exists as a visible remnant in the area. The church itself gives some orientation, though the college building remains unlocated. Anyone visiting with an interest in the period would do well to read the Civil Survey entries beforehand; the language of seventeenth-century land documentation is dense but rewarding, and the survey, edited by Robert Simington and published in 1945, remains the clearest primary source for what the building was called and who owned the land it stood on.