R. Pain listed as architects. The trouble is, the bridge was actually constructed between 1836 and 1838. The discrepancy is small, but it neatly illustrates how the official memory of a place can quietly diverge from the physical record. What the plaque does not mention at all is the older, stranger story beneath the water: the present seven-arch limestone bridge is believed to rest on pier foundations from the medieval bridge it replaced, a detail identified through survey drawings made as far back as 1814.

The crossing of the River Shannon at this point has a history that stretches well before the Pain brothers' elegant rock-faced arches. According to the Urban Survey of Limerick compiled by Bradley and colleagues in 1989, a bridge in Limerick was destroyed by Domhnall Mór Ua Briain in 1176, suggesting a river crossing of some kind had existed here since Viking times, though scholars note some uncertainty about its precise location. The Shannon bridge itself appears to date from the reign of King John, who ruled from 1199 to 1216, making it a product of the same Norman ambition that produced the nearby castle on King's Island. By 1358, the citizens of Limerick had received a royal grant to extend that medieval bridge and add towers to it, specifically to help repel attacks. The previous structure had fourteen arches; the present one has seven, broader and more accessible by design, built to improve links with the agricultural districts of County Clare. Both Thomond Bridge and the nearby Baal's Bridge appear repeatedly on sixteenth and seventeenth century maps, confirming that these were well-established crossings long before anyone thought to fix a commemorative tablet to the stonework.

The bridge carries road traffic today and is straightforward to reach, sitting immediately beside King John's Castle on King's Island in Limerick city. The plaque is mounted on the road side of the parapet and is legible without any special effort, though it rewards a slow reading once you know the dates do not quite add up. The pointed curved breakwaters, which project upstream and downstream from the piers to deflect the river's flow, are worth noticing from the riverbank or from the castle grounds, where the full geometry of the seven arches is visible. The Shannon runs broad and tidal here, and the bridge looks different depending on the light and the state of the water.