The evidence is slender but suggestive. John W. de Courcey, writing in his 1996 study of the Liffey, notes at pages 204 to 7 a possible early mill race at Islandbridge. A mill race is an artificial channel cut to divert a portion of a river's flow and direct it with enough force to turn a waterwheel, and where one exists it implies not only a mill but a degree of civil planning: someone chose the site, organised the labour, and maintained the works over time. The qualifier "possible" is doing real work in de Courcey's account, and no firm date is attached to the feature. What can be said is that Islandbridge sits at a point where the Liffey narrows and the gradient would have made a diversion practical, and that early ecclesiastical and Scandinavian settlements in the wider area are well attested. Whether this particular channel belongs to an Irish monastic context, a Viking-age industrial operation, or a later medieval arrangement remains unresolved.

Visitors approaching the site today will find themselves in a public green space on the south bank of the Liffey, easily reached from the city centre on foot or by bus. The memorial gardens nearby are well signposted, but the riverbank itself rewards a slower look, particularly at lower water levels when the profile of the channel is easier to read. There are no interpretive markers pointing to the mill race, and the feature is not visually dramatic in the way that upstanding stonework might be. What you are really looking at, or trying to look at, is a slight anomaly in the way the water and the bank sit in relation to each other, the kind of thing that repays patience and a copy of de Courcey to hand.