St Mary's Chapel is the kind of place that survives only as a footnote, a name that appears in historical records and then disappears from the physical world, leaving no ruin, no outline in the ground, and no firm coordinates on any map.

The chapel is mentioned in sources dating to around 1495 and again around 1570, suggesting it had a continuous, if modest, existence through the later medieval period. By 1577, it had been formally annexed to the neighbouring St Werburgh's Church, one of Dublin's oldest parish churches and a significant presence in the city since at least the twelfth century. Annexation of this kind was not unusual; smaller chapels that could no longer sustain independent congregations or clergy were often absorbed into larger neighbouring parishes, their identities gradually dissolving into the administrative structures of the more prominent institution. The historian Howard Clarke, writing in 2002, noted the chapel's former existence to the south of St Werburgh's, but was unable to pin down its precise location, which tells its own story about how thoroughly a building can be erased by centuries of urban development and rebuilding.

There is, truthfully, nothing to visit here in any conventional sense. The area around St Werburgh's, on Werburgh Street near Dublin Castle, has been continuously inhabited and rebuilt across many centuries, and whatever physical trace St Mary's Chapel once left has long since been built over or cleared away. For those interested in the archaeology of absence, the church of St Werburgh's itself remains open at certain times and is well worth attention on its own terms. The site of the vanished chapel, somewhere in the streets to the south, is the kind of place that rewards thinking about rather than looking at, a reminder that medieval Dublin was considerably denser with religious buildings than the surviving fabric suggests.