The Emperor Marcus AureliusThis larger-than-life bronze equestrian statue, sculpted to celebrate his military victories 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; a copy stands outdoors. (Tibor Bognar/Alamy)