Mexico City's Centro Historico was once called Tenochtitlán, founded in 1325 atop a an island in Lake Texcoco. The seers of the wandering Aztec tribe had received a vision, telling to found their great city in a spot where an eagle, perched on a cactus, was devouring a serpent. Their quest ended here.

The lake has long since been drained, though the eagle still flies over the old island - today enormous Plaza del la Constitución (more commonly called the Zócalo) - as part of an enormous Mexican flag. The seat of government since Aztec times, the Centro Historico is surrounded by fantastic architecture from every age: The Templo Mayor, an Aztec Temple that was once North America's most important; the Metropolitan Cathedral, the largest and oldest cathedral in the hemisphere; and the Torre Latinoamericana, once the tallest building in Latin America, and still one of the world's largest earthquake-resistant structures.

The Historic Center stretches on for some 700 blocks, however, packed with museums, parks, hotels, restaurants, and nightlife options; it is more populous than many countries and a world unto itself. An afternoon's exploration offers a taste of its offerings; a lifetime would not be long enough to see it all.

The Mexico City Centro Historico (or Historic Center) is wrapped around the Zócalo, more properly called Plaza de la Constitución. While there are dozens of car parks in the area, it is more easily explored on foot, and there are several metro stops serving the region. The most convenient is the Zócalo station on Metro Line 2. Buses radiate outward along the major avenues toward the farthest reaches of the city, and taxis swarm through the congested streets.

During national celebrations, such as Independence Day (September 15), the area is filled with inebriated revelers. During national protests - and this is Mexico, so these happen fairly often - the Zócalo can devolve into a showdown between riot police and [insert opposition group here]. In either case, foreigners are advised to stay on the edge of the crowd and stay alert for pickpockets.