What bridge did Leonardo da Vinci design to swing rapidly across a river?

Leonardo da Vinci designed a revolving bridge intended to swing rapidly across a river.

The bridge was conceived as a military engineering device. Its rotating arrangement could let troops cross a waterway and then move the bridge aside, leaving the route open to ships or making the crossing harder for an opponent to use.

Leonardo’s bridge studies emphasized portability, stability, and speed of deployment. A counterweight helped balance the structure as it turned, and the design could be assembled from relatively straightforward structural members rather than relying on a permanent stone crossing.

This concept is different from a conventional drawbridge, whose deck usually pivots upward around a hinge. Leonardo’s revolving bridge instead turns horizontally around a supporting point, making its movement the defining feature.