On the southern face of this old limestone crossing of the River Barrow, just north of Monasterevin, a partially blocked arch lurks beneath the vegetation at the western end, lower than the rest and long since sealed up. It is easy to miss, and most people presumably do. The bridge carries five visible arches across roughly forty metres of water, but that half-hidden sixth suggests an earlier configuration, an older structure absorbed into what stands today.

The bridge, also known as Ballagh Bridge, is built from roughly coursed, undressed limestone blocks, and while it has been repaired and repointed over the centuries, with concrete reinforcing the bases of the piers, a good deal of what appears to be original fabric survives. Four triangular cutwaters on the upstream, northern face run the full height of the bridge and widen at the top into small pedestrian refuges set into the parapet, a common feature on older Irish bridges that allowed people to step clear of passing traffic. The cutwaters on the southern face are much reduced by comparison, reaching only to the base of the piers. According to the Countess of Drogheda, writing in 1902 to 1903, the bridge may have been crossed by the Earl of Essex in 1599 during his ill-fated Irish campaign, and later by Cromwell's forces on their march to demolish Lea Castle in what is now County Laois. Both attributions carry the usual uncertainty that attaches to routes taken by armies across a landscape of few reliable roads, but the bridge's location on the Barrow, a significant natural boundary, makes it a plausible crossing point for either expedition.