License, verbatimCC0
The Metropolitan Museum of Art: Open Access, Creative Commons Zero (CC0). Flagged isPublicDomain=true in the museum's own record.
Albrecht Dürer. The Middle Section of the Entryway to the Central Portal, the Columns Decorated by Sirens and Sleeping Soldiers Behind, from the Arch of Honor, proof, dated 1515, printed 1517-18, 1515. The Metropolitan Museum of Art.