License, verbatimPD
The National Gallery of Art: open access image with no usage restrictions under the NGA's open access policy (openaccess=1 in the Gallery's published_images dataset).
Filippo Vasconi, after Gabriele Valvassori. The Prima Macchina for the Chinea of 1729: Hercules Germanicus in the Theater of Virtues, 1729. National Gallery of Art, Washington.