The Aniene, formerly known as the Teverone, is a 99-kilometer river in Lazio, Italy. It originates in the Apennines at Trevi nel Lazio and flows westward past Subiaco, Vicovaro, and Tivoli to join the Tiber just north of Rome. It thus formed the principal valley east of ancient Rome and was an important water source as the city's population expanded. The falls at Tivoli were noted for their beauty. Historic bridges across the river include the Ponte Nomentano, Ponte Salario, and Ponte di San Francesco, all of which were originally fortified with towers.