Mexico City is one of the most populous cities in the world, and one of the most historic. Because of its vast size, tourists may have a hard time deciding what sites to visit, but a Top 10 list is a good start.
Get to the heart of the city. The Plaza de la Constitucion (Zocalo) is the heartbeat of the city, the nation's capital. Located in el Centro Historico (Historic Center), this plaza is the second largest public square in the world (Moscow's Red Square is the largest, and Beijing's Tiananmen Square is third largest). At the center of the plaza is a tall pole with a huge national flag of Mexico. Something is always going on here, from dances and cultural events to music concerts or political protests. The Plaza, located at a Metro stop, is surrounded by several others of the city's top 10 sights: the Catedral Metropolitana, Palacio Nacional and Templo Mayor. It is within walking distance of the Palacio de Bellas Artes, el Torre Latinoamericana and Alameda Park.
See the Catedral Metropolitana (Metropolitan Cathedral). One of the largest cathedrals in the city, it contains several architectural styles because it was built over 250 years. It is on the north side of the Plaza de la Constitucion. Materials used to construct the cathedral came from the destroyed Aztec temple on the site. Due to the nature of Mexico City's soil, the cathedral is slowly sinking. Stroll through the cathedral's vast interior to see many religious displays and examples of architecture; you may also hear the massive pipe organ or the cathedral bells.
Visit the Palacio Nacional (National Palace). On the entire east side of the main plaza, this government building is most famous for several Diego Rivera murals.
Explore the Templo Mayor (Great Temple). These are the archaeological ruins of the Aztec Templo Mayor, which was dedicated to the Aztec gods of Tlaloc (rain) and Huitzilopochtli (war). This was the primary temple and focal point of the the Aztec capital of Tenochtitlan. Many of the temple's materials were used by the Spanish to construct the adjacent Catedral Metropolitana.
Visit the Palacio de Bellas Artes (Palace of Fine Arts), Torre Latinoamericana (Latin American Tower) and Alameda Park. Palacio de Bellas Artes was completed in 1934 and is one of the city's finest theaters and performance venues. The interior contains several murals by Rivera, Orozco, Siqueiros, and Tamayo. Visitors to Mexico City often enjoy a performance of the Ballet Folklorico at this venue. Adjacent to the Fine Arts Palace is the Torre Latinoamericana, completed in 1956 with 44 floors. Visitors may pay to ride an elevator to an upper level observation deck for 360-degree views of sprawling Mexico City, the Valley of Mexico, and the surrounding mountains and volcanoes. Look directly down to the east to see Plaza de la Constitucion, Metropolitan Cathedral and National Palace. Look southwest to see Chapultepec Park. Nearby the Tower and the Fine Arts Palace is Alameda Park, the city's first park, dating to the 1500s.
Walk in Bosque de Chapultepec (Chapultepec Park). At the southwestern end of Paseo de la Reforma, this is the city's largest and most sprawling park, 1,600 acres. Many pathways lead through acres of forests and lakes. Chapultepec Castle is on a hill in the park and was once home of Maximilian I and Empress Carlota, and is now home to the National History Museum. There are excellent views of Paseo de la Reforma and the park from the castle's various balconies. Also in the park are a zoo, a lake with boat rentals, an amusement park, Los Pinos (the official residence and offices of the President of Mexico), the National Auditorium and several other museums, including the Modern Art Museum, Natural History Museum, Children's Museum, and the excellent and massive National Museum of Anthropology.
Explore the Museo Nacional de Antropologia (National Museum of Anthropology). Considered one of the great museums of the world, Museo Nacional de Antropologia contains perhaps the world's largest collection of pre-Columbian artifacts and art. The museum is massive and is arranged according to each of the pre-Columbian cultures, with halls and galleries dedicated to each. The central courtyard is famous for its vast square concrete umbrella. Popular exhibit halls include those dedicated to the Olmec, Maya and Aztec civilizations.
See Xochimilco. In the southern part of the city, these are the last remnants of the series of lakes that were here in the time of the Aztecs. The area contains a series of canals, where visitors may take rides on brightly colored gondolas. The canals are all that is left of the Chinampas (floating gardens) type of agriculture developed by the Aztecs.
See the Basílica de Nuestra Señora de Guadalupe (Basilica of Our Lady of Guadalupe). Guadalupe is the patron saint of Mexico. The image of Guadalupe that appeared to Juan Diego on the very hill (Tepeyac Hill) where the Basilica is constructed is an important and easily recognizable national symbol. There are actually two basilicas on this hill, an old and a more modern one. Construction of the old basilica began in 1531, and the new in 1976. The apron of Juan Diego with the image of Guadalupe is displayed for all to see in the new basilica. It is likely the most important religious building in Mexico and possibly in all of Latin America; it is the second most visited Roman Catholic religious site after Vatican City.
Take a day trip to Teotihuacan, a pre-Aztec archaeological site about 25 miles from Mexico City. At its cultural height, 150 to 450 A.D., it was the largest city in the world, with a population of over 200,000. The site contains two large pyramids -- Pyramid of the Sun and Pyramid of the Moon -- and many smaller pyramids flanking the Avenida de los Muertos (Avenue of the Dead). The Temple of Quetzalcoatl is also worth seeing. Visitors may climb to the top of the two large pyramids for spectacular views of the site, surrounding countryside and mountains.