License, verbatimCC0
The Metropolitan Museum of Art: Open Access, Creative Commons Zero (CC0). Flagged isPublicDomain=true in the museum's own record.
Giovanni Battista Piranesi. View of the Campo Vaccino (Roman Forum with the Temple of Castor and Pollux to right), from "Vedute di Roma" (Roman Views), part II, ca. 1750–78. The Metropolitan Museum of Art.