What type of bridge did Leonardo da Vinci design as a quickly assembled military crossing?

Leonardo da Vinci designed a self-supporting bridge as a quickly assembled military crossing.

The design appears in Leonardo’s notebooks and uses interlocking timber pieces arranged so that the structure supports itself. Soldiers could theoretically assemble it without nails, ropes, or permanent foundations, making it useful for crossing streams or defensive ditches during a campaign.

The bridge is often described as a “self-supporting” or “self-supporting arched” bridge. That description refers to its construction method, not to a modern suspension bridge. Leonardo also drew other bridge concepts, including a large single-span bridge intended for the Ottoman sultan Bayezid II, but that was a separate project.

The surviving drawings are designs rather than evidence that Leonardo personally built the bridge. Modern demonstrations have shown that the interlocking principle can work when the pieces are cut and positioned correctly. The idea illustrates Leonardo’s interest in practical mechanics, military engineering, and structures that could be transported and assembled rapidly.