Leonardo da Vinci's experimental machine-gun design displayed 33 barrels in one arrangement. The device was a multi-barrel cannon concept intended to increase the rate of fire compared with a single gun.
Leonardo arranged the barrels in three rows, with each row containing 11 guns. The arrangement could be fired in sequence while another row cooled or was reloaded. A wheeled frame was intended to make the weapon easier to move across a battlefield.
Calling it a machine gun can create a modern misunderstanding. Leonardo's weapon still relied on gunpowder, individual barrels, and manual loading; it was not an automatic firearm. It also belongs to a broader group of Renaissance artillery ideas, many of which remained drawings rather than completed machines.