The River Tagus is the longest river in the Iberian Peninsula, flowing approximately 1,007 kilometers. It originates in the Sierra de Albarracín mountains in Spain and travels westward through the country before emptying into the Atlantic Ocean near Lisbon, Portugal. The river plays a significant role in the region's ecology and economy. It supports various ecosystems and provides water for agriculture and industry. The Tagus River is also important for transportation, with several cities, including Toledo and Lisbon, situated along its banks.