The Tiber (, Latin Tiberis, Italian Tevere, ) is the third-longest river in Italy, rising in the Apennine Mountains in Emilia-Romagna and flowing through Umbria and Lazio, where it is joined by the Aniene river, to the Tyrrhenian Sea. It drains a basin estimated at . The river has achieved lasting fame as the main watercourse of the city of Rome, founded on its eastern banks. The river rises at Mount Fumaiolo in central Italy and flows in a generally southerly direction past Perugia and Rome to meet the sea at Ostia. Popularly called flavus (“the blond”), in reference to the yellowish colour of its water, the Tiber has heavily advanced at the mouth by about since Roman times, leaving the ancient port of Ostia Antica inland. However, it does not form a proportional delta, owing to a strong north-flowing sea current close to the shore, to the steep shelving of the coast, and to slow tectonic subsidence.