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. Veduta degli avanzi del Foro di Nerva, l'arcade et la muraille (The Forum of Augustus [erroneously called the Forum of Nerva]), 1757. The Metropolitan Museum of Art.