(in Spanish: Ciudad de México, México, D.F. or simply México) is the capital city of Mexico. It is the most important economic, industrial and cultural center in the country, and the most populous city with 8,720,916 inhabitants in 2005. Greater Mexico City (Zona Metropolitana del Valle de México) incorporates 58 adjacent municipalities of Mexico State and 1 municipality of the state of Hidalgo, according to the most recent definition agreed upon by the federal and state governments. In 2006 Greater Mexico City had a population of 19.2 million, making it the largest metropolitan area in the western hemisphere and the second[3] largest in the world. In 2005, it ranked the eighth in terms of GDP (PPP) among urban agglomerations in the world. Along with São Paulo it is the only Beta global city with 8 points in Latin America.

Mexico City is also the Federal District (Distrito Federal in Spanish, and hence the abbreviation D.F.). The Federal District is coextensive with Mexico City: both are governed by a single institution and are constitutionally considered to be the same entity. This has not always been the case. The Federal District, created in 1824, was integrated by several municipalities, one of which was the municipality of Mexico City. As the city began to grow, it engulfed all other municipalities into one large urban area. In 1928, all municipalities within the Federal District were abolished, an action that left a vacuum in the legal status of Mexico City vis-à-vis the Federal District, even though for most practical purposes they were traditionally considered to be the same entity. In 1993, to end the sterile discussions about whether one concept had engulfed the other, or if any of the two entities had any existence in lieu of the other, the 44th Article of the Constitution of Mexico was reformed to clearly state that Mexico City is the Federal District, seat of the Powers of the Union and capital of the United Mexican States.

The Historic Center (Centro Histórico) and the "floating gardens" of Xochimilco in the southern borough have been declared World Heritage Sites by the UNESCO. Famous landmarks in the Historic Center include the Plaza de la Constitución (Zócalo), the main central square with its time clashing Spanish-era Metropolitan Cathedral and Palacio Nacional, and ancient Aztec temple ruins Templo Mayor ("Major Temple") are all within a few steps of one another. (The Templo Mayor was discovered in 1978 while workers were digging to place underground electric cables.)

The most recognizable icon of Mexico City is the golden Angel of Independence, found on the wide, elegant avenue Paseo de la Reforma, modeled by the order of the Emperor Maximilian of Mexico after the Champs-Élysées in Paris. This avenue was designed in the XIX Century to connect the National Palace (seat of government) with the Castle of Chapultepec, the imperial residence. Today, this avenue is an important financial district in which the Mexican Stock Market is located. Another important avenue is the Avenida de los Insurgentes, which extends 28.8 km (18 miles) and is one of the longest single avenues in the world.

The Chapultepec park houses the Castle of Chapultepec, now a museum on a hill that overlooks the park and its numerous museums, monuments and the national zoo and the National Museum of Anthropology (which houses the Aztec Calendar Stone). Another magnificent piece of architecture is the Fine Arts Palace, a stunning white marble theatre/museum whose weight is such that it has gradually been sinking into the soft ground below. Its construction began during the presidency of Porfirio Díaz and ended, after being interrupted by the Mexican Revolution in the 1920s. The Plaza of the Three Cultures in the Tlatelolco neighbourhood, and the shrine and Basilicas of Our Lady of Guadalupe are also important sites. There is a double decker bus, known as the "Turibus", that circles most of these sites, and has timed audio describing the sites in multiple languages as they are passed.

In addition, the city has around 160 museums, over 100 art galleries, and some 30 concert halls, all of which maintain a constant cultural activity during the whole year. It has the fourth highest number of theatres in the world after New York, London and Toronto, and it is the city with the highest number of museums in the world. In many locales (Palacio Nacional and the Instituto Nacional de Cardiología, to name a few), there are murals painted by Diego Rivera. He and his wife Frida Kahlo lived in the southern suburb of Coyoacán, where several of their homes, studios, and art collections are open to the public. The house where Leon Trotsky was initially granted asylum and finally murdered in 1940 is also in Coyoacán.

In addition, there are several restored haciendas that are now restaurants, such as the San Ángel Inn, the Hacienda de Tlalpan and the Hacienda de los Morales, all of which are stunning remnants of Mexican history and house some of the best food in the world.

Mexico City is the location of National Autonomous University of Mexico (UNAM). UNAM is the second-oldest (established in 1551) and the largest (with 269,000 students) university in the Americas. Three Nobel laureates and most of Mexico's modern-day presidents are among its former students. UNAM conducts 50% of Mexico's scientific research and has presence all across the country with satellite campuses and research centers. The National Autonomous University of Mexico ranks 74th in the Top 200 World University Ranking published by The Times Higher Education Supplement in 2006,[44] making it the highest ranked Spanish-speaking university in the world. The sprawling main campus of the university, known as Ciudad Universitaria, was named a World Heritage Site by the UNESCO in 2007, during the period of Juan Ramón de la Fuente as the President of UNAM.

The second largest higher-education institution is the National Polytechnic Institute (IPN) (which includes, among many other relevant centers, the Centro de Investigación y de Estudios Avanzados (Cinvestav), where high-level research is performed about very different scientific and technological disciplines such as physics, mathematics, neurosciences, and many others). Other major higher-education institutions in the city include the Metropolitan Autonomous University (UAM), the ITAM, the ITESM (3 campuses), the Universidad Panamericana (UP), the Universidad La Salle, the Universidad del Valle de Mexico (UVM), the Universidad Anáhuac, the Alliant International University, the Universidad Iberoamericana, El Colegio de México (Colmex), and the Centro de Investigación y Docencia Económica (CIDE).

Contrary to what occurs in the constituent states of the Mexican federation, the curriculum of Mexico City's public schools is managed by the federal level Secretary of Public Education. The whole funding is allocated by the government of Mexico City (in some specific cases, such as El Colegio de México, funding comes from both the city's government and other public and private national and international entities).

A very special case is that of El Colegio Nacional, created during the governmental period of Miguel Alemán Valdés to have, in Mexico, an institution very similar to the College of France. The very selected and privileged group of Mexican scientists and artists belonging this institution (the membership is lifelong; some of the current members are Mario Lavista, Ruy Pérez Tamayo, José Emilio Pacheco, Marcos Moshinsky, Guillermo Soberón Acevedo, and many others) have the obligation of disclosing their works among the general population, through conferences and public events such as concerts and recitals.

Mexico City is the country's most important center for the television, advertising, music, newspaper and book publishing industries. Two national newspapers are published here, El Universal and Excélsior, as well as important regional newspapers such as Reforma and La Jornada. Other major papers include Milenio, Crónica, El Economista and El Financiero.

The two largest media companies in the Spanish-speaking world, Televisa and TV Azteca, are headquartered in Mexico City. Other local television networks include Canal 11, Canal 22, Cadena Tres, Teveunam and 11 free-access channels.

There are 60 radio stations operating in the city and a huge number of local community radio stations.

Mexico City is one of the most important cultural centers in the world boasting more museums than any other city. It is also the fourth city in number of theaters after New York City, London and Toronto.

Having been capital of a vast pre-Hispanic empire, the richest viceroyalty within the Spanish Empire, and capital of the Mexican federation, Mexico City has a rich history of artistic expressions. Since the Mesoamerican pre-Classical period the inhabitants of the settlements around Lake Texcoco produced many works of arts, some of which are today displayed at the world-renown National Museum of Anthropology and the Templo Mayor Museum. While many pieces of pottery and stone-engraving have survived, the great majority of the Amerindian iconography was destroyed during the Conquest of Mexico.

Mexico City offers a huge array of culinary experiences. Restaurants specializing in the regional cuisines of Mexico's 32 states are available in the city. Also available are restaurants representing a broad spectrum of international cuisines, including French, Italian, Polish, Hungarian, Portuguese, Spanish (including Spanish regional variations such as Castillian, Asturian, Galician and Basque), Chinese, Japanese, Korean, Thai, Lebanese, Moroccan, as well as Peruvian, Argentinean, and Brazilian.