Seven arches carry it across the river, and those arches come in three distinct sizes, which is unusual enough on its own. What makes the bridge genuinely curious, though, is the evidence of its own history written into the stonework: two vertical joins can be detected in the arches, suggesting the bridge was extended not once but twice, with earlier, narrower crossings gradually widened to accommodate changing needs.

The arrangement of the arches gives a further clue to the bridge's logic. The river itself is directed through the two larger central arches, while the remaining five, smaller in scale, handle the floodplain on either side. This kind of design, where a bridge is built wide enough to span not just the channel but the land that periodically becomes river, was a practical response to the seasonal behaviour of Irish waterways. The Meath lowlands are flat and prone to flooding, and a crossing that failed every winter was no crossing at all. Each phase of expansion presumably responded to the same pressure, whether that was heavier traffic, flood damage, or a change in the river's course. The joins in the stonework are the only record left of those decisions.