License, verbatimCC0
The Metropolitan Museum of Art: Open Access, Creative Commons Zero (CC0). Flagged isPublicDomain=true in the museum's own record.
Stefano della Bella. Two cannons, two soldiers seen from the back seated to the right, from "Equipment needed for Fortification" (Recueil de diverses pièces très nécessaires à la fortification), ca. 1638–43. The Metropolitan Museum of Art.