Pons Mosellae
About
Engineers drove fresh oak into the Moselle in 71 CE, replacing the crossing of 17 BCE whose timbers effectively founded the city. Tree-ring dating pinned the new piles to that single year. The deck carried the great highway from Lyon to Cologne straight toward the forum, and it was still the working river crossing under Trajan in 117 CE. Builders replaced it a third and final time with basalt piers in the 140s.
What happened here
Piers are set on cofferdams — a ring of driven piles, pumped dry, filled with concrete that sets under water. They are built with a cutwater pointing upstream to split the current and the ice. The span above may be stone arches or timber on stone, and timber is not a poor relation: it is cheaper, faster, and replaceable. Roads approach on an embankment so the crossing stays level. Tolls are common, shrines at either end are usual, and the inscription names whoever paid. Floods are the enemy; a bridge is inspected after every big one, and the scour around the piers is packed with rubble. A bridge fixes a town's position for a thousand years, which is why so many are still standing.
Sources
Nearby
Roman Maps shows the empire frozen at 11 August 117 CE, the day Trajan died — its moment of greatest territorial extent. Explore the full map →