What kind of bridge did Leonardo da Vinci design to support itself without nails or mortar?

Leonardo da Vinci designed a self-supporting bridge that could stand without nails or mortar.

The bridge used interlocking wooden elements arranged so that the structure’s own weight helped hold it together. This made it a portable engineering concept: a group could carry the pieces and assemble a crossing without permanent foundations or conventional fasteners.

Leonardo’s bridge belongs to his studies of military engineering and temporary field structures. Such a design could be useful when troops needed to cross an obstacle quickly, although the surviving drawing is evidence of a proposal rather than proof of large-scale military deployment.

It is sometimes called a self-supporting or self-locking bridge. That description distinguishes it from a drawbridge, which moves to control access, and from a suspension bridge, which relies on cables or chains.