Poggenmühlen Bridge

This guide to the Poggenmuehlen Bridge in Hamburg starts with an engineering problem from the early 1880s: the marshy silt pulled from the river Elbe here would not hold a barn, let alone six-story brick warehouses. It follows the crew that decided to sink thousands of oak tree trunks down through the mud until they hit firm sand, and the political pressure behind it, since joining Germany's customs union in 1881 meant walling off and rebuilding an entire harbor quarter fast. Stand on the bridge itself, where two canals, the Wandrahmsfleet and the Hollaendischbrookfleet, meet directly beneath your feet.