In September 2007 one French archaeologist got lucky. He was diving in the murky waters of the Rhône River at Arles, in the south of France, in search of ancient remains on the riverbed. He emerged holding a finely carved, life-size marble head. As he lifted it up out of the water, in one of those classic discovery moments, the director of the team shouted, “Putain, mais c’est César—Damn, it’s Caesar.”

It was, in other words, a portrait of arguably the most famous Roman who ever lived: Julius Caesar, conqueror of Gaul, charismatic dictator, populist autocrat, and, finally, victim of assassination on the ides of March, 44 B.C. (an event immortalised by William Shakespeare, among many other writers and painters). He is one of the people from antiquity who—alongside Cleopatra, perhaps—later generations have most wanted to meet face-to-face. Tracking down the likeness of the real Caesar has proved an irresistible sport.