The chief river in central Italy, the Tiber rises as a small southwestern flow in the Apennines near Arretium, separating Etruria from Umbria and Latium. It flows 250 miles to the Mediterranean Sea at Ostia, joined by the Nar river after 110 miles, where its swift current is navigable but dangerous, and by the Teverone river 70 miles further on, where it becomes truly navigable, three miles north of Rome. Inside Rome, 22 miles from the coast, the Tiber is about 300 feet wide, 12-18 feet deep, and swift-moving, regularly overflowing its banks with heavy rains. Augustus created the office of curatores riparum et alvei Tiberis to deal with this recurring problem (Suetonius, Vita Divi Augusti 37). Muddy from the silt it carried (the Roman poets called it flavus tiberis), it formed Tiber Island at one bend in Rome and Insula Sacra, an island sacred to Venus 4 miles from the coast at Ostia,which was the ancient source of salt deposits.
The Tiber River is the symbolic father of Rome, guiding Aeneas in a dream to the future site of Rome (Vergil, AEN. VIII. 31-67), bearing the infant twins Romulus and Remus to safety, and serving as a safe and profitable pathway for early Roman commerce.