Transtiberim (modern Trastevere) is a district that packs many surprises for us. While it is true that the proto-Romans of the Iron Age had their first contact with the outside world in the form of a Sabine colony from Cures that settled on the Quirinal Hill, and after bitter struggle the Romans absorbed them, Rome's first meeting with an international power came at the edge of the Tiber, in the form of powerful Etruria. One of the most powerful and wealthy cities, Etruscan Veii, took shape just ten miles up the road from Rome. As Rome grew, Veii would be a mortal threat for centuries.

Carthaginian ships sailed up the Tiber from time to time, more to do business with the Etruscans than the Romans. The Greeks and the Etruscans did business with each other, and the already sophisticated Etruscans learned much from the Greeks, which they passed along to the Romans. But the Romans had their own hard-headed beliefs, and in the end they conquered that entire world (and more!) that lay across the Tiber.

Cover: a naumachia, or mock sea battle (with real people fighting and dying), by Ulpiano Checa, 1894. There were five such venues in Transtiberim, according to the Regionary Catalog. It is doubtful that the Circus Maximus or Colosseum were ever flooded for this purpose; especially the Colosseum, which had extensive understructures that would have been destroyed if filled by water. Likewise, the Circus Maximus might have been undermined, and might have collapsed, if filled with water. There are scattered mentions of some temporary wooden amphitheaters filled with water, but we can be sure that the heavy-duty flooding, with plenty of elbow room for bloody battles, was amply served by the earth-dug naumachia.