The Emperor Marcus Aurelius This larger-than-life bronze equestrian statue, sculpted to celebrate his military victories or shortly after his death in 180 C.E., shows the emperor holding up his hand in the conventional imperial greeting. More than twenty equestrian statues could be seen in late imperial Rome, but this is the only one to survive. In the sixteenth century Michelangelo built one of the major plazas of Rome around it, although now the original has been moved to a museum for better preservation and a copy stands outdoors.

(Piazza Campodoglio, Rome, Italy/Prisma/UIG via Getty Images)