What makes it worth a closer look is the evidence built into its own structure: the upstream face shows semicircular arches constructed from voussoirs, the wedge-shaped stones that form an arch, that are noticeably different from those used in the rest of the bridge. This mismatch strongly suggests the bridge was widened at some point, most likely during the nineteenth century, giving it a kind of geological layering in reverse, with later construction grafted onto the older core.

By the time the Civil Survey of 1654 to 1656 was compiled, this crossing was already being recorded as the "old bridge of Beallanadarragh", a name that implies it was considered ancient even then. The bridge spans 31 metres and is just over five metres wide, with five segmental arches that rise gradually in height as they approach the centre, a design choice that gives the whole structure its distinctive hump. The stonework is roughly cut with only faint traces of hammer dressing, suggesting early construction methods rather than the more refined masonry of later centuries. On the upstream side, four cutwaters, projecting piers designed to divide the river current and protect the structure, originally supported four pedestrian refuges where someone crossing on foot could step aside to let a cart pass. Three of those refuges survive intact, each roughly two and a half metres wide and just under one and a half metres deep. Just to the north, on the Offaly bank, a castle site and a mill once stood, a cluster of features that points to this as a place of genuine strategic and economic importance on the river.

The bridge still carries road traffic, and the arch façade has been re-pointed in recent times, with the underside of the vaulting rendered smooth. Those repairs are visible if you look closely, layered over the older rough stonework and sitting alongside the evidence of the nineteenth-century widening, making the bridge itself something of a compressed record of how crossing the Little Brosna has mattered, and changed, over several centuries.