Lima is the capital and the largest city of Peru. It is located in the valleys of the Chillón, Rímac and Lurín rivers, in the central coastal part of the country, overlooking the Pacific Ocean. Together with the seaport of Callao, it forms a contiguous urban area known as the Lima Metropolitan Area. With a population of more than 9 million, Lima is the most populous metropolitan area of Peru and the third-largest city in the Americas, behind São Paulo and Mexico City. Lima was founded by Spanish conquistador Francisco Pizarro on January 18, 1535, as Ciudad de los Reyes. It became the capital and most important city in the Spanish Viceroyalty of Peru. Lima is home to one of the oldest institutions of higher learning in the New World. The National University of San Marcos, founded on May 12, 1551, during the Spanish colonial regime, is the oldest continuously functioning university in the Americas.