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. Avanzi del Tempio detto di Apollo nella Villa Adriana vicino a Tivoli (Hadrian's Villa. Remains of the Smaller Palace [Formerly called the Temple of Apollo]), ca. 1768. The Metropolitan Museum of Art.