Leonardo da Vinci is credited with sketching the Architronito, a steam-powered cannon concept.
The name is commonly rendered as Architronito or Architonnerre. In the description associated with Leonardo's notebooks, water would be heated in a cannon chamber until the resulting steam pressure expelled a projectile. The idea appears to combine artillery with an early understanding of steam pressure.
The device is not evidence that Leonardo built a practical steam cannon. Historians debate the interpretation and feasibility of the surviving notes, and the design would have faced severe problems involving heat, pressure, sealing, and metal strength. It is therefore best presented as a proposed artillery concept.
The Architronito is distinct from Leonardo's more conventional cannon studies. Those designs focused on mechanical loading, multiple barrels, or improved handling, while this one relied on heated water and expanding steam.