St. Donagh's Well, once a small pool roughly four and a half metres across and shaded by a large ash tree, stood on the southern bank of a river that has since been deepened and reshaped. The river management works that transformed the area erased whatever surface features the well once had, and no physical trace remains above ground today.

The well's former life is documented in some detail. Caoimhín Ó Danachair, writing in 1958, drew on the Ordnance Survey Name Books to describe water that was considered remarkably good and widely sought out for the curing of ailments of all kinds. A local woman named Mrs. King provided an account of St. John's Eve practice, the eve of the 24th of June, midsummer in the old Irish calendar, when small groups would come to the well, drink from it, and leave votive rags tied nearby as offerings. This custom, known across Ireland at holy wells, involved hanging a strip of cloth on a branch or bush beside the water, the idea being that as the rag decayed, an illness or burden might lift with it. By the time Ó Danachair was writing, even these modest devotions had lapsed. A 1985 account by Appleyard confirmed the well's fate more bluntly, noting that it had been covered in, and that it lay within the grounds of Donaghmede House, where it had once been a popular place of devotion.

For anyone curious enough to look, the site sits within what is now a public park corridor along the river in Kilbarrack Upper on Dublin's northside. There is nothing to see in the conventional sense; no stonework, no trough, no marker. The interest here is almost entirely archival. Those drawn to the layered, often invisible history of urban green spaces may find something quietly compelling in the fact that a place once believed to carry healing properties now passes entirely unnoticed beneath an ordinary stretch of parkland.