The diversity of Mexico City's attractions springs from its complex history. From simple bustling mercados to museums filled with treasures of artistic and historic significance, Mexico City has layers and layers of cultural richness to explore.

Mexico City was built on the ruins of the ancient city of Tenochtitlan. A downtown portion of the city, comprising almost 700 blocks and 1,500 buildings, is designated the Centro Histórico (Historic Center). The area has surged in popularity, and once-neglected buildings are being converted into fashionable shops and restaurants, recalling its former colonial charm.

Remember that this is a major Latin city; dress is more professional and formal here than in other parts of the country. The altitude keeps the temperature mild, which is often a surprise for travelers with preconceptions of Mexico as perpetually hot. In summer, always be prepared for rain, which falls for an hour or two almost daily. In winter, carry a jacket or sweater -- stone museums are chilly inside, and when the sun goes down, the outside air gets quite cold. If you want to blend in with the crowd, black is always the new black, especially in the winter.

Día de las Bicis -- The traffic-congested streets of Mexico City can be daunting for drivers, let alone travelers who wish to reach their destination on two wheels. However, every Sunday bicycles rule. As part of a program called Muévete en Bici (Get Moving on a Bike), the city shuts down the middle lanes of Reforma -- from near the entrance of Chapultepec Park to the zócalo, although the route can change depending on construction or special events -- one of the city's most prominent avenues, so that up to 10,000 cyclists, and their friends the runners, walkers, and even the odd stilt walker, can have free rein of the pavement. The best part is that the route passes by some of the city's most famous monuments and museums, many of which are free to the public on Sundays. The streets are cleared for bicyclists from 8am to 2pm.

In early 2010 the city launched EcoBici (tel. 55/5005-2424; www.ecobici.df.gob.mx), a bike-sharing service. With more than 80 stations scattered across Roma, Condesa, Zona Rosa, and Centro Historico, this is by far the most convenient option for commuters and leisurely riders alike. Although the program was designed with locals in mind, visitors are also welcome to pay the annual fee of 300 pesos at one of the customer service centers -- either on Rosas Moreno 152 B. in Colonia San Rafael or Nuevo Leon 78 in Condesa. In exchange you receive an EcoBici card, which grants you access to the red bikes parked at the stations. Simply return the bike when you've finished to any EcoBici station.

Festival de México en el Centro Histórico -- In March of every year, a series of concerts, cultural events, art exhibits, and public performances takes place in -- and in honor of -- Mexico City's historic downtown district. For more information or a calendar of events, check out the Festival de México website (www.festival.org.mx).

Mexico City Fun-derground -- Who says you need a lot of money to have a great time while traveling? For the cost of Metro fare (5 pesos!) you can get a true sense of Mexico City's quirkiness. Most major stations are also miniature underground malls, complete with fast food, snack stalls, and shops.

Zócalo station features dioramas and large photographs of the different periods in the history of the Valley of Mexico. The Pino Suárez station is home to the preserved ruins of a pyramid dedicated to the Aztec god Ehecatl. In addition to being the god of the wind, Ehecatl was also responsible for the cardinal directions, which is appropriate because Pino Suárez is one of the Metro's most important hubs. Science geeks will not want to miss a trip to the La Raza station in the northern part of the city. The "Túnel de la Ciencia" (Tunnel of Science), a permanent exhibition maintained by the Universidad Nacional Autónoma de México (UNAM), links the platforms for lines 3 and 5 and features giant slides of fractals and embryos as well as a glow-in-the-dark rendition of the universe on the ceiling. Director Paul Verhoeven used the Insurgentes station as a backdrop for the 1990 Arnold Schwarzenegger flick Total Recall, painting the Metro cars gray in order to portray his vision of the future.

If you find yourself in the company of well-off Chilangos -- perhaps at a gallery in Polanco or a restaurant in San Angel -- mention that you rode the Metro. You'll likely be met with stunned expressions, as many members of the upper class have never set foot underground and will think you're either crazy or brave for trying it.

Mighty Tenochtitlan -- What 16th-century metropolis was home to approximately 200,000 inhabitants, had intricate botanical and zoological gardens filled with thousands of exotic species, and had markets where as many as 40,000 people went to trade a menagerie of goods on a regular basis? London? Nope -- there were only 50,000 people living there in 1500. Barcelona? No, sir; the Spaniards had not yet conceived of the concept of botanical gardens. How about Constantinople? Nope. The European soldiers who helped conquer this city said its markets outshone even the Turkish bazaars.

The city in question was called Tenochtitlan, the capital of the mighty Aztec empire. We know the area today as Mexico City.

When the Spanish arrived, they must have felt as though they had landed on another planet; the Aztecs had constructed an entire metropolis on the boggy marshes of Lake Texcoco. The city was intersected by a series of causeways, one of which was 8km (5 miles) long and wide enough for eight horsemen abreast to pass through. Up to 50,000 canoes plied through these causeways and corresponding canals, transporting everything from corn to brightly colored fabrics and obsidian blades. The famous Spanish chronicler Bernal Díaz wrote that "with such wonderful sites to gaze on we did not know what to say, or if this was real that we saw before our eyes," in his account of the siege of Tenochtitlan in True Story of the Conquest of New Spain.

Unfortunately, the Spaniards hadn't traveled thousands of miles just to send home pretty postcards -- after repeated attacks, famine, and a smallpox epidemic, Tenochtitlan fell on August 13, 1521, and Cuautéhmoc, the last Aztec emperor, was taken prisoner.

If you'd like to get a better feel for Tenochtitlan, the Museo de la Ciudad de México has a fine collection of maps and pictographic representations of the time period, and a few farmers still grow their produce using ancient floating garden methods in Xochimilco.

Note: This information was accurate when it was published, but can change without notice. Please be sure to confirm all rates and details directly with the companies in question before planning your trip.