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. Demonstration panel showing technique for raising travertine and marble blocks for the construction of the tomb of Cecilia Metella, Rome, from "Le Antichità Romane", 1756. The Metropolitan Museum of Art.