Leonardo da Vinci proposed a 240-metre bridge across Istanbul’s Golden Horn in 1502.
Leonardo sent the design to Ottoman Sultan Bayezid II, who wanted a crossing between Constantinople and the district of Galata. The design used a single, broad masonry arch rather than many smaller arches in the water.
The bridge was never built in Leonardo’s lifetime. Its unusually long span made it an ambitious engineering proposal for the early sixteenth century, although modern engineers have studied the design and found its structural form plausible.
The proposal is sometimes confused with a later reconstruction at Ås in Norway, which was built at a much smaller scale. That modern footbridge demonstrates the shape of Leonardo’s concept but is not the original Istanbul bridge.