Tagus, << TAY guhs, >> River, also called Tajo, is the longest river of the Iberian Peninsula of southwest Europe. It rises in central Spain and flows west across Portugal to the Atlantic Ocean. The river is 626 miles (1,007 kilometers) long and drains an area of about 31,000 square miles (80,300 square kilometers). The mouth of the Tagus, at Lisbon, Portugal, forms one of Europe’s most important harbors.
