License, verbatimCC0
The Metropolitan Museum of Art: Open Access, Creative Commons Zero (CC0). Flagged isPublicDomain=true in the museum's own record.
Mathäus Küsel. The Triumph of Austria; Leopold I at center, mounted on a reared horse, atop a military trophy; surrounded by equestrian portraits of the Holy Roman Emperors; set design from 'Il Pomo D'Oro', 1668. The Metropolitan Museum of Art.