License, verbatimCC0
The Metropolitan Museum of Art: Open Access, Creative Commons Zero (CC0). Flagged isPublicDomain=true in the museum's own record.
Adriaen Collaert. Plate 6: equestrian statue of Nero, seen from behind, the Great Fire of Rome in the background, from 'Roman Emperors on Horseback', ca. 1587–89. The Metropolitan Museum of Art.