Tiber River, Italian Fiume Tevere, is a river of Europe and the second longest Italian river (after the Po), rising on the slope of Monte Fumaiolo, a major summit of the Tuscan-Emilian Apennines. The Tiber is 252 miles (405 km) long. Twisting in a generally southerly direction through a series of scenic gorges and broad valleys, it flows through the city of Rome and enters the Tyrrhenian Sea of the Mediterranean near Ostia Antica. Its major tributaries are the Chiascio, Nestore, Paglia, Nera, and Aniene.

Source: Britannica