The greater Mexico City metropolitan area is one of the world's largest and most populated, with an estimate of about 20 million people living in the region. It is shaped roughly like an oval of about 60 by 40 kilometers, built on the dry bed of Lake Texcoco, and surrounded on three sides by tall mountains and volcanoes such as the Ajusco, the Popocatepetl and the Ixtlacihuatl. Mexico City proper (with an estimated population of between 8 to 9 million) is in the Federal District (Spanish: Distrito Federal or D.F.), a federally-administered area (that is, not part of any Mexican state) which acts as the capital of Mexico. The rest of the metropolitan area extends beyond it into Mexico State, which surrounds D.F. on three sides. Legally and practically speaking, Mexico City is the same as the Federal District, and that is where most tourists will spend the majority of their time when visiting or staying in the city.

The city is located 2200 meters above the sea level. Some people not used to high places have experienced difficulty when breathing, however these symptoms fade a few minutes after arrival. Difficulty breathing due to pollution, however, can potentially last a bit longer.

Mexico City's night life is like all other aspects of the city; it's huge. There is an enormous selection of venues: clubs, bars, restaurants, cafes, and variations and combinations thereof to choose from. There is incredible variation, from ultramodern lounges in Santa Fe and Reforma, to centuries-old dance halls in Centro and Roma. There are also pubs in Tlalpan and Coyoacán and clubs of every stripe in Insurgentes, Polanco, Condesa and the Zona Rosa.