License, verbatimCC0
The Metropolitan Museum of Art: Open Access, Creative Commons Zero (CC0). Flagged isPublicDomain=true in the museum's own record.
Anonymous. Neptune rising from the sea and bearing a staff, accompanied by two horse-headed sea creatures, reverse copy after a series of engravings by Cherubino Alberti of mythological scenes after Polidoro da Caravaggio, ca. 1550–1600. The Metropolitan Museum of Art.