The "Via Aurelia" crossed the Tiber River by way of the bridge "Pons Aemilius", then exited Rome from its western side. After the Emperor Aurelian built a wall around Rome ( 270–273 CE), the "Via Aurelia" exited from the "Porta Aurelia" (gates). The road then ran about to "Alsium" on the Tyrrhenian coast, north along the coast to "Vada Volaterrana", Cosa, and "Pisae" (modern Pisa). There the original length of the Via Aurelia terminated. This was an especially important route during the early and middle Republic because it linked Rome, "Cosa", and "Pisae". "Cosa" was an important colony and military outpost in Etruria, and "Pisae" was the only port between "Genua" and Rome. Consequently, it was an important naval base for the Romans in their wars against the Ligurians, Gauls and Carthaginians.