The major river that flows through Spain is the Tagus River. Originating in the mountains of eastern Spain, it flows across the country and eventually empties into the Atlantic Ocean near Lisbon, Portugal. The Tagus is the longest river in the Iberian Peninsula and plays a vital role in the history, culture, and economy of the regions it traverses. It has served as a source of water, transportation, and inspiration for artists and writers throughout the centuries.