La Paz, officially known as Nuestra Señora de La Paz, also named Chuqi Yapu (Chuquiago) in Aymara, is the seat of government and the de facto national capital of the Plurinational State of Bolivia. With an estimated 789,541 residents as of 2015, La Paz is the third-most populous city in Bolivia. Its metropolitan area, which is formed by La Paz, El Alto and Viacha, makes up the most populous urban area in Bolivia, with a population of 2.3 million. It is also the capital of the La Paz Department.