Mexico City, or City of Mexico (Spanish: Ciudad de México, American Spanish: [sjuˈða(ð) ðe ˈmexiko]; abbreviated as "CDMX"), is the capital and most populous city of Mexico. As an "alpha" global city, Mexico City is one of the most important financial centers in the Americas. It is located in the Valley of Mexico (Valle de México), a large valley in the high plateaus at the center of Mexico, at an altitude of 2,240 metres (7,350 ft). The city consists of sixteen municipalities (previously called boroughs). The 2009 estimated population for the city proper was approximately 8.84 million people, with a land area of 1,485 square kilometres (573 sq mi). According to the most recent definition agreed upon by the federal and state governments, the Greater Mexico City population is 21.2 million people, making it the second-largest metropolitan area of the western hemisphere, behind New York City, the tenth-largest agglomeration, and the largest Spanish-speaking city in the world. The Greater Mexico City has a gross domestic product (GDP) of US$411 billion in 2011, making Mexico City urban agglomeration one of the economically largest metropolitan areas in the world. The city was responsible for generating 15.8% of Mexico's Gross Domestic Product and the metropolitan area accounted for about 22% of total national GDP. As a stand-alone country, in 2013, Mexico City would be the fifth-largest economy in Latin America—five times as large as Costa Rica's and about the same size as Peru's. Mexico’s capital is both the oldest capital city in the Americas and one of two founded by Amerindians (Native Americans), the other being Quito. The city was originally built on an island of Lake Texcoco by the Aztecs in 1325 as Tenochtitlan, which was almost completely destroyed in the 1521 siege of Tenochtitlan, and subsequently redesigned and rebuilt in accordance with the Spanish urban standards. In 1524, the municipality of Mexico City was established, known as México Tenochtitlán, and as of 1585 it was officially known as Ciudad de México (Mexico City). Mexico City served as the political, administrative and financial center of a major part of the Spanish colonial empire. After independence from Spain was achieved, the federal district was created in 1824. After years of demanding greater political autonomy, residents were given the right to directly elect a Head of Government and the representatives of the unicameral Legislative Assembly by popular vote in 1997. Ever since, the left-wing Party of the Democratic Revolution (PRD) has controlled both of them. In recent years, the local government has passed a wave of liberal policies, such as abortion on request, a limited form of euthanasia, no-fault divorce, and same-sex marriage. On January 29, 2016, it ceased to be called the Federal District (Spanish: Distrito Federal or D.F.) and is now in transition to become the country's 32nd federal entity, giving it a level of autonomy comparable to that of a state. Because of a clause in the Mexican Constitution, however, as the seat of the powers of the federation, it can never become a state, lest the capital of the country be relocated elsewhere.