Uncovered during street redevelopment works in the early 1990s, as Dublin Corporation undertook the broader Temple Bar refurbishment project, the well measures roughly six metres deep and under a metre in diameter. Its structural fabric dates to around 1700, when Eustace Street was first laid out, and it drew on fresh groundwater from an area that sat close to the River Poddle, which was tidal at that point. What makes it stranger still is the question of whether something much older, and considerably more sacred, once occupied the same ground.

The well on Eustace Street has long been associated with St. Winifred, a seventh-century Welsh saint whose cult spread well beyond her homeland. A holy well, in the Irish and broader Celtic Christian tradition, is a natural or constructed water source believed to hold curative or sacred properties, typically dedicated to a saint and used as a site of prayer or pilgrimage. According to researcher Halpin, writing in 1992, the veneration of St. Winifred may have reached Dublin between the eleventh and thirteenth centuries, during a period when the city maintained close ties with Chester. The famous shrine of St. Winefride at Holywell, near Chester, remains one of the most celebrated pilgrimage sites in Britain, and it appears Dublin had its own echo of that devotion. The well may also have been connected to the Augustinian Friary of Holy Trinity, founded in the thirteenth century and located approximately fifty metres to the east, in what is now Cecilia Street. In 1757, Dr. John Rutty, whose published work on Irish mineral waters remains a useful historical source, recorded testing the water of what he called the well of St. Winifred on Eustace Street. Whether the well he sampled and the one uncovered in the 1990s are the same structure remains unresolved; the stonework visible today does not date to the medieval period, though the two records may well refer to the same source.

The well is situated outside The Norseman on Eustace Street, which runs through the Temple Bar area and is easily reached on foot from Dame Street or the quays. It is not a dramatic feature, and visitors who are not looking for it will walk past without pause. The surrounding streetscape is busy and commercial, which makes the presence of the well feel all the more incongruous. There is no formal interpretation on site, so arriving with some background knowledge makes the visit considerably more rewarding.