San Francisco de Quito, most often called Quito, is the capital city of Ecuador in northwestern South America. It is located in north-central Ecuador in the Guayllabamba river basin, on the eastern slopes of Pichincha, an active stratovolcano in the Andes mountains. With a population of approximately 1,397,698 according to the last census (2001), and, as estimated by the municipality, approximately 2,504,991 in 2005, Quito is the second most populous city in Ecuador, after Guayaquil.