Alexander the Great This mosaic of Alexander on horseback comes from the Roman city of Pompeii. It depicts the Battle of Issus (333 B.C.E.), in which Greek forces, although considerably outnumbered, defeated the Persian army, led personally by Emperor Darius III. (Museo Archeologico Nazionale, Naples, Italy/De Agostini Picture Library/G. Nimatallah/Bridgeman Images)