Holy wells are traditional sacred springs, often associated with a patron saint and historically visited for healing or devotion, and this one appears on the historical Ordnance Survey maps under two entirely different dedications within a few decades of each other. The identity of the well shifted quietly from one saint to another, and then, eventually, the well itself disappeared beneath development.

The 1837 edition of the Ordnance Survey Ireland six-inch map records it as St. Dennis' Well, but by the time the Cassini edition was produced it had been renamed St. Philip's Well. The 1863 twenty-five-inch map goes a step further, annotating it as 'St. Philip's Well (Site of)', suggesting that even by the mid-nineteenth century the physical well was already lost or obscured. The ground on which it stood was formerly part of a demesne to the north-west of Clontarf Castle, as noted by both Dillon-Cosgrave in 1977 and Ó Danachair in 1958. Stiles Lane, the older route associated with the area, was eventually absorbed into housing development, severing whatever remained of the landscape that once surrounded the well.

The location is identified locally as a tarmacadamed area at the front of No. 35 Stiles Road. There is nothing to mark the spot officially, and the surrounding streetscape gives little indication that anything of historical significance lies underfoot. For anyone interested in the layers of devotional geography that still persist, largely unacknowledged, across Dublin's northern suburbs, this is the kind of place that rewards a certain tolerance for anticlimax. The well itself is gone, but the fact that local knowledge has preserved its approximate location at all is quietly telling.