Set over 2400m above sea level in a shallow mountain bowl, and crammed with over twenty million people, Mexico City is one of the world’s most densely populated urban areas, the capital is nowhere near as intimidating as you might expect. Nonetheless, you may still prefer to take it in a couple of days at a time, taking days off to visit the places, all of which are possible as day trips. The city radiates out from the Zócalo, or main square, as much the heart of the modern capital as it was of the Aztec city that once sat here. Immediately to its west, in the streets between the Zócalo and the garden known as the Alameda, is the city’s main commercial area. Beyond that, the glitzy Zona Rosa, with trendy Condesa to its south, stretches towards Chapultepec Park home to the incredible Museo Nacional de Antropología and the rich enclave of Polanco, while Avenida de los Insurgentes leads down to the more laid-back barrios of San Ángel and Coyoacán. Around the outer edges of the city are shantytowns, built piecemeal by migrants from elsewhere in the country. Hidden among these less affluent communities are a number of gems, such as the pyramids of Tenayauca, Santa Cecilia and Cuicuilco, and the canals of Xochimilco. It’s hardly surprising that Cortés and his followers should have been so taken by their first sight of Tenochtitlán, capital of the Aztecs. Built in the middle of a lake traversed by great causeways, it was a beautiful, strictly regulated, stone-built city of 300,000 residents. The Aztec people (or, as they called themselves, the Mexica) had arrived at the lake in around 1345, after years of wandering and living off what they could scavenge or pillage from settled communities. According to Aztec legend, their patron god Huitzilopochtli had ordered them to build a city where they found an eagle perched on a cactus devouring a snake this they duly saw on an island in the middle of the lake. It is this legend that is the basis of the nopal, eagle and snake motif that forms the centrepiece of the modern Mexican flag and you’ll see the motif everywhere from coins and official seals to woven designs on rugs. The lake proved an ideal site. Well stocked with fish, it was also fertile, once the Aztecs had constructed their chinampas, or floating gardens of reeds, and virtually impregnable, too: the causeways, when they were completed, could be flooded and the bridges raised to thwart attacks (or escape, as the Spanish found on the Noche Triste). The island city eventually grew to cover an area of some thirteen square kilometers, much of it reclaimed from the lake, and from this base the Aztecs were able to begin their programme of expansion: first, dominating the valley by a series of strategic alliances, war and treachery, and finally, in a period of less than a hundred years before the Conquest, establishing an empire that demanded tribute from and traded with the most distant parts of the country.

As many as two million Mexicans died during the Revolution and many more lost their property, their livelihood or both. In desperation, thousands fled to rapidly industrializing Mexico City in search of jobs and a better life. Between 1910 and the mid-1940s the city’s population quadrupled and the cracks in the infrastructure quickly became gaping holes. Houses couldn’t be built quickly enough to cope with the seven-percent annual growth, and many people couldn’t afford them anyway, so shantytowns of scraps of metal and cardboard sprang up. Most neighborhoods had little or no water supply and sanitation was an afterthought. Gradually, civic leaders tried to address the lot of its citizens by improving the services and housing in shantytowns, but even as they worked a new ring of slums mushroomed just a little further out. As the city expanded, transport became impossible and the city embarked on building the Metro system in the late 1960s. The 175th and most recent Metro station was completed in 2000; a twelfth Metro line is expected to open in 2010. Urban growth continues today: some statisticians estimate that there are a thousand new arrivals each day, mainly from rural areas with high unemployment, and the city now extends beyond the limits of the Distrito Federal and out into the surrounding state of México. Despite the spread, Mexico City remains one of the worlds most densely and heavily populated cities, with an unenviable list of major social and physical problems, including an extreme vulnerability to earthquakes the last big one, in 1985, killed over 9000 people, made 100,000 homeless and left many of the city’s buildings decidedly skewed. The traditional centre of the city is the Zócalo, or Plaza Mayor, officially called Plaza de la Constitución. The heart of both ancient Tenochtitlán and of Cortés’s city, it’s surrounded by the oldest streets, largely colonial and unmodernized. To the east, the ancient structures degenerate rapidly, blending into the poorer areas that surround the airport. Westwards, avenidas Madero and Juárez lead to the Alameda, the small park that marks the edge of the old city centre. Here are the Palacio de Bellas Artes, the main post office and the landmark Torre Latinoamericana. Carry on west past here and you get into an area, between the ugly bulk of the Monumento a la Revolución and the train station, where you’ll find many of the cheaper hotels. Turn slightly south and you’re amid the faded elegance of the Paseo de la Reforma, which leads down to the great open space of Chapultepec Park, recreation area for the city’s millions, and home of the Museo Nacional de Antropología and several other important museums. On the northwest side as you head down Reforma is a sedate, upmarket residential area, while to the southeast is the Zona Rosa with its shopping streets, expensive hotels and constant tourist activity. To the south, the Zona bleeds into Condesa, which in recent years has become the fashionable place to eat, drink and party. To the west, the northern flank of Chapultepec Park is lined by the flashy high-rise hotels of Colonia Polanco, among the city’s chicest districts and home to many of the finest shops and restaurants. Avenida de los Insurgentes crosses Reforma about halfway between the Alameda and Chapultepec Park. Said to be the longest continuous city street in the world, Insurgentes bisects Mexico City more or less from north to south, and is lined with modern commercial development. In the south it runs past the suburbs of San Ángel and Coyoacán to the University City, and on out of Mexico City by the Pyramid of Cuicuilco. Also in the southern extremities of the city are the waterways of Xochimilco, virtually the last remains of the great lagoons. In the outskirts, Insurgentes meets another important route, the Calzada de Tlalpan, which runs due south from the Zócalo past the eastern side of Coyoacán and a couple of fine museums. To the north, Insurgentes heads past the northbound bus station, then sweeps out of the city via the basilica of Guadalupe and Indios Verdes. The northern extension of Reforma, too, ends up at the great shrine of Guadalupe, as does the continuation of the Calzada de Tlalpan beyond the Zócalo.

For all its size and frantic pace, once you’re used to the city, it is surprisingly easy to get around, with an efficient and very cheap public transport system as well as reasonably priced taxis or also you can take Uber, Cabify and other mobile trendy services. You’ll want to walk around the cramped streets of the centre, but remember the altitude walking gets tiring quickly, especially for the first day or so. If you’re heading for Chapultepec or the Zona Rosa, you’re better off taking the bus or Metro it’s an interesting walk all the way down Reforma, but a very long one. As for the outer suburbs, you’ve got no choice but to rely on public transport. You’ll save a lot of hassle if you avoid travelling during rush hour. Tours that take in the city and often include the surrounding area are available from most of the more expensive hotels, and from operators such as American Express. The government of the DF runs a one-hour city-centre sightseeing tour on buses in the style of old trams leaving from Juárez by Bellas Artes, but the commentary is in Spanish only. One of the best city tours is with Turibus, who run open-top double-deckers on two routes: a northern route taking in the city centre, and a southern route that heads down Insurgentes Sur to Coyoacán and the University. You can get on and off the bus at any stage en route; stops for the northern route include the Zócalo (República de Brasil, on the west side of the cathedral), the Benito Juárez Monument on the south side of the Alameda, and El Ángel on Reforma; at Las Cibeles (Plaza Madrid) in Roma, you can change from the northern to the southern route. Both run every 30–40 minutes). Each circuit takes around three hours, and the commentary comes in a choice of languages including English. There’s also a night route Thursdays and Fridays, run by a single bus doing two circuits only, each taking around two hours. Mexico City is home to some of the best private hospitals in the country; Hospital Ángeles, Hospital ABC and Médica Sur to name a few. The national public healthcare institution for private-sector employees, IMSS, has its largest facilities in Mexico City including the National Medical Center and the La Raza Medical Center and has an annual budget of over 6 billion pesos. The IMSS and other public health institutions, including the ISSSTE (Public Sector Employees' Social Security Institute) and the National Health Ministry (SSA) maintain large specialty facilities in the city. These include the National Institutes of Cardiology, Nutrition, Psychiatry, Oncology, Pediatrics, Rehabilitation, among others.

The heart of Mexico City is the Zócalo, built by the Spanish right over the devastated ceremonial centre of the Aztec city of Tenochtitlán. Extraordinary uncovered ruins chief of which is the Templo Mayor provide the Zócalo’s most compelling attraction, but there’s also a wealth of great colonial buildings, among them the huge cathedral and the Palacio Nacional with its striking Diego Rivera murals. You could easily spend a couple of days in the tightly packed blocks hereabouts, investigating their dense concentration of museums and galleries, especially notable for works by Rivera and his “Big Three” companions, David Siqueiros and José Clemente Orozco. West of the Zócalo the centro histórico stretches through the main commercial district past the Museo Nacional de Arte to the sky-scraping Torre Latinoamericana and the Palacio de Bellas Artes with its gorgeous Art Deco interior. Both overlook the formal parkland of the Alameda, next to which you’ll find a number of museums, principally the Museo Franz Mayer, which houses an excellent Alameda-related arts and crafts collection, and the Museo Mural Rivera, with the artist’s famed Dream of a Sunday Afternoon in the Alameda. Further west, the Revolution Monument heralds the more upmarket central suburbs, chiefly the Zona Rosa, long known as the spot for plush shops and restaurants, though that title has largely been usurped by swanky Polanco and hipper Condesa. The vast paved open space of the Zócalo (Metro Zócalo) properly known as the Plaza de la Constitución was once the heart of Aztec Tenochtitlán, and is today one of the largest city squares in the world after Beijing’s Tiananmen Square and Moscow’s Red Square. The city’s political and religious centre, it takes its name from part of a monument to Independence that was planned in the 1840s for the square by General Santa Anna. Like most of his other plans, this went astray, and only the statue’s base (now gone) was ever erected: el zócalo literally means “the plinth”. By extension, every other town square in Mexico has adopted the same name. It’s constantly animated, with pre-Hispanic revivalist groups dancing and pounding drums throughout the day and street stalls and buskers in the evening. Stages are set up here for major national holidays and, of course, this is the place to hold demonstrations. Over 100,000 people massed here in March 2001 to support the Zapatistas after their march from Chiapas in support of indigenous people’s rights; in July 2006 the square proved too small to contain the millions of demonstrators who gathered to challenge the result of that year’s presidential election, a contest widely believed especially in the left-leaning DF to have been fixed. Spreading out from the Zócalo, the crowds reached as far as Reforma. Though you’re not guaranteed to see any protests, among the Zócalo’s more certain entertainments is the ceremonial lowering of the national flag from its giant pole in the centre of the plaza each evening at sundown (typically 6pm). A troop of presidential guards march out from the palace, strike the enormous flag and perform a complex routine at the end of which the flag is left, neatly folded, in the hands of one of their number. With far less pomp, the flag is quietly raised again around half an hour later. You get a great view of this, and of everything else happening in the Zócalo, from the rooftop La Terraza restaurant/bar in the Hotel Majestic at the corner of Madero. The Zócalo does, of course, have its less glorious aspects. Mexico City’s unemployment rate is tellingly reflected by the people who line up on the west side of the cathedral seeking work, each holding a little sign indicating their trade.

The Catedral Metropolitana holds the distinction of being the largest church in Latin America. Like so many of the city’s older, weightier structures, the cathedral has settled over the years into the soft, wet ground beneath the tilt is quite plain to see, despite extensive work to stabilize the building. The first church on this site was constructed only a couple of years after the Conquest, using stones torn from the Temple of Huitzilopochtli, but the present structure was begun in 1573 to provide Mexico City with a cathedral more suited to its wealth and status as the jewel of the Spanish empire. The towers weren’t completed until 1813, though, and the building incorporates a plethora of architectural styles. Even the frontage demonstrates this: relatively austere at the bottom where work began soon after the Conquest, it flowers into full Baroque as you look up, and is topped by Neoclassical cornices and a clock tower. If you want to climb the clock tower, join one of the guided tours that start roughly hourly from the information desk to the right as you enter. Inside, although the size of the cathedral is striking, the chief impression is that it’s a rather gloomy space, with rows of dimly lit side chapels. It is enlivened mostly by the Altar de los Reyes, a vast gilt reredos built of wood between 1718 and 1737 behind the main altar that features effigies of European kings and queens as well as two oil paintings, the Assumption of the Virgin and Adoration of the Kings. Fans of ornate handiwork will also appreciate the detailed work in gold and wood on the central coro (choir). Next door, the Sagrario Metropolitano, despite its heavy, grey Baroque facade and squat, bell-topped towers, feels both lighter and richer inside, with its exuberant churrigueresque decoration and liberal use of gold paint. It was originally built as the parish church, and performs most of the day-today functions of a local church, such as baptisms and marriages.

Mexico City has a subtropical highland climate, due to its tropical location and high elevation. The lower region of the valley receives less rainfall than the upper regions of the south; the lower boroughs of Iztapalapa, Iztacalco, Venustiano Carranza and the west portion of Gustavo A. Madero are usually drier and warmer than the upper southern boroughs of Tlalpan and Milpa Alta, a mountainous region of pine and oak trees known as the range of Ajusco. The average annual temperature varies from 12 to 16 °C (54 to 61 °F), depending on the altitude of the borough. The temperature is rarely below 3 °C (37 °F) or above 30 °C (86 °F). The lowest temperature ever registered was −4.4 °C (24.1 °F), and the highest temperature on record is 33.9 °C (93.0 °F). Overall precipitation is heavily concentrated in the summer months, and includes dense hail. The central valley of Mexico rarely gets precipitation in the form of snow during winter; the two last recorded instances of such an event were on March 5, 1940 and January 12, 1967. The region of the Valley of Mexico receives anti-cyclonic systems. The weak winds of these systems do not allow for the dispersion, outside the basin, of the air pollutants which are produced by the 50,000 industries and 4 million vehicles operating in and around the metropolitan area. The area receives about 820 millimetres (32.3 in) of annual rainfall, which is concentrated from June through September/October with little or no precipitation the remainder of the year. The area has two main seasons. The rainy season runs from June to October when winds bring in tropical moisture from the sea. The dry season runs from November to May, when the air is relatively drier. This dry season subdivides into a cold period and a warm period. The cold period spans from November to February when polar air masses push down from the north and keep the air fairly dry. The warm period extends from March to May when tropical winds again dominate but do not yet carry enough moisture for rain. The World Bank has sponsored a project to curb air pollution through public transport improvements and the Mexican government has started shutting down polluting factories. They have phased out diesel buses and mandated new emission controls on new cars; since 1993 all new cars must be fitted with a catalytic converter, which reduces the emissions released. Trucks must use only liquefied petroleum gas (LPG). Also construction of an underground rail system was begun in 1968 in order to help curb air pollution problems and alleviate traffic congestion. Today it has over 201 km (125 mi) of track and carries over 5 million people every day. Fees are kept low to encourage use of the system and during rush hours the crush is so great, that authorities have reserved a special carriage specifically for women. Due to these initiatives and others, the air quality in Mexico City has begun to improve, with the air becoming cleaner since 1991, when the air quality was declared to be a public health risk for 355 days of the year.

On the other hand, Mexico City is also home to large communities of expatriates and immigrants, most notably from the rest of North America (U.S. and Canada), from South America (mainly from Argentina and Colombia, but also from Brazil, Chile, Uruguay and Venezuela), from Central America and the Caribbean (mainly from Cuba, Guatemala, El Salvador, Haiti and Honduras); from Europe (mainly from Spain, Germany and Switzerland, but also from Czech Republic, Hungary, France, Italy, Ireland, the Netherlands, Poland and Romania), from the Middle East (mainly from Egypt, Lebanon and Syria); and recently from Asia-Pacific (mainly from China and South Korea). Historically since the era of New Spain, many Filipinos settled in the city and have become integrated in Mexican society. While no official figures have been reported, population estimates of each of these communities are quite significant. Mexico City is home to the largest population of U.S. Americans living outside the United States. Current estimates are as high as 700,000 U.S. Americans living in Mexico City, while in 1999 the U.S. Bureau of Consular Affairs estimated over 440,000 Americans lived in the Mexico City Metropolitan Area. The majority (82%) of the residents in Mexico City are Roman Catholic, higher than the national percentage, though it has been decreasing over the last decades. Many other religions and philosophies are also practiced in the city: many different types of Protestant groups, different types of Jewish communities, Buddhist, Islamic and other spiritual and philosophical groups. There are also growing numbers of irreligious people, whether agnostic or atheist. Mexico City offers a variety of cuisines. Restaurants specializing in the regional cuisines of Mexico's 31 states are available in the city. Also available are an array of international cuisines, including Canadian, French, Italian, Croatian, Spanish (including many regional variations), Jewish, Lebanese, Chinese (again with regional variations), Indian, Japanese, Korean, Thai, Vietnamese; and of course fellow Latin American cuisines such as Argentine, Brazilian, and Peruvian. Haute, fusion, kosher, vegetarian and vegan cuisines are also available, as are restaurants solely based on the concepts of local food and slow Food. Mexico City is known for having some of the freshest fish and seafood in Mexico's interior. La Nueva Viga Market is the second largest seafood market in the world after the Tsukiji fish market in Japan. The city also has several branches of renowned international restaurants and chefs. These include Paris' Au Pied de Cochon and Brasserie Lipp, Philippe (by Philippe Chow); Nobu, Morimoto; Pámpano, owned by Mexican-raised opera legend Plácido Domingo. There are branches of the exclusive Japanese restaurant Suntory, Rome's famed Alfredo, as well as New York steakhouses Morton's and The Palm, and Monte Carlo's BeefBar. Three of the most famous Lima-based Haute Peruvian restaurants, La Mar, Segundo Muelle and Astrid y Gastón have locations in Mexico City. For the 2014 list of World's 50 Best Restaurants as named by the British magazine Restaurant, Mexico City ranked with the Mexican avant-garde restaurant Pujol (owned by Mexican chef Enrique Olvera) at 20th best. Also notable is the Basque-Mexican fusion restaurant Biko (run and co-owned by Bruno Oteiza and Mikel Alonso), which placed outside the list at 59th, but in previous years has ranked within the top 50. Mexico's award-winning wines are offered at many restaurants, and the city offers unique experiences for tasting the regional spirits, with broad selections of tequila and mezcal. At the other end of the scale are working class pulque bars known as pulquerías, a challenge for tourists to locate and experience. Mexico City offers an immense and varied consumer retail market, ranging from basic foods to ultra high-end luxury goods. Consumers may buy in fixed indoor markets, mobile markets (tianguis), from street vendors, from downtown shops in a street dedicated to a certain type of good, in convenience stores and traditional neighborhood stores, in modern supermarkets, in warehouse and membership stores and the shopping centers that they anchor, in department stores, big-box stores and in modern shopping malls. The city's main source of fresh produce is the Central de Abasto. This in itself is a self-contained mini-city in Iztapalapa borough covering an area equivalent to several dozen city blocks. The wholesale market supplies most of the city's "mercados", supermarkets and restaurants, as well as people who come to buy the produce for themselves. Tons of fresh produce are trucked in from all over Mexico every day. The principal fish market is known as La Nueva Viga, in the same complex as the Central de Abastos. The world-renowned market of Tepito occupies 25 blocks, and sells a variety of products. A staple for consumers in the city is the omnipresent "mercado". Every major neighborhood in the city has its own borough-regulated market, often more than one. These are large well-established facilities offering most basic products, such as fresh produce and meat/poultry, dry goods, tortillerías, and many other services such as locksmiths, herbal medicine, hardware goods, sewing implements; and a multitude of stands offering freshly made, home-style cooking and drinks in the tradition of aguas frescas and atole.