The structure carries the name of the townland immediately to its west, Castle Ellis, and sits in a stretch of County Kilkenny where the Barrow and its feeders have shaped movement through the landscape for centuries.

The bridge appears on a map of Gowran drawn by White in 1710 or 1711, labelled there as the 'Long Bridg', which suggests it was already a recognised crossing of some standing at that date. Its construction is limestone rubble, roughly coursed, with squared voussoirs, the wedge-shaped stones that form an arch and lock it in compression, visible on the western face. Two cutwaters project from the piers on either side, angled to split the current and protect the stonework from the force of the river. The parapet runs to about a metre in height and has been capped at some point with concrete of a rounded profile, a modest later intervention that sits above the older stonework. Elongated approach walls, stone-capped, extend the structure on both sides. There is a possibility that fabric dating to the seventeenth century survives within the bridge, and that what exists today represents an earlier, narrower crossing that was widened at some later stage, though the precise history of that widening is not documented.