Beneath the current John's Bridge, completed in 1910, lie the layered remains of several earlier crossings, including a lost 18th-century structure whose story involves medieval grave slabs repurposed as riverbed ballast, a temporary flood bridge held together with forged iron shoes, and an Iron Age fish-trap woven from post-and-wattle, the same technique used to build walls in early medieval houses, here adapted to catch fish in a river current.

The sequence of crossings at this spot stretches back centuries, but the most dramatic rupture came in 1763, when a catastrophic flood destroyed most of the bridges on the Nore. In the immediate aftermath, softwood timbers were driven into the riverbed in three parallel lines to form a temporary crossing, many of them still fitted with their iron shoes when excavated. The more permanent replacement came in 1772: a three-arch masonry bridge, 45 metres long with a slightly humped profile, designed by George Smith and built by the contractor William Colles. When excavated by archaeologist Ian Doyle in 2001, two of the bridge's substantial piers, each 12 metres long and 4 metres wide, were uncovered, along with the original timber shuttering used to form their bases. Around those piers, builders had packed the riverbed with medieval grave slabs, probably removed from nearby St Mary's parish church, to protect the foundations from scour. Slabs intended for burial had been quietly pressed into service as engineering fill. The 1772 bridge itself was eventually superseded, and most of its masonry abutments were removed as part of a later flood relief scheme, though one section of abutment still survives on the east bank of the river.