Mexico City is the capital and largest city of Mexico. In addition, it is the largest metropolitan area in the western hemisphere, with a population of over 19 million people. At an altitude of 7,349 feet above sea level, Mexico City is one of the world's most polluted cities.
The Aztecs originally built Mexico City in 1325. According to Aztec legend, their civilization was built upon the place where an eagle had caught a snake upon a cactus. This omen was apparently realized in 1325 and the Aztecs built their city, known as Tenochtitlan, on an island on Lake Texoco. The Aztec civilization thrived for nearly 200 years until Spanish explorer Hernan Cortes conquered the Aztecs in 1521. Cortes claimed all of Mexico for Spain, destroyed Tenochtitlan, which was said to be more magnificent than any European city, and returned to Spain with untold amounts of treasure, precious gems, gold and silver. In 1524, the city was completely rebuilt and served as the capital of New Spain.
After Mexico gained independence from Spain in 1821, Mexico City became the center of Mexico's Federal District, a concept similar to America's District of Columbia. In 1847, the United States and Mexico signed the Treaty of Guadalupe-Hidalgo in Mexico City, a treaty which forced Mexico to cede much of the American southwest as a result of the Mexican-American War.
After the Mexican Revolution of 1910, a deadly Civil War that claimed over a million lives, Mexico City's population began to expand rapidly. By 1950, there were over three million people who called Mexico City home. Nevertheless, political unrest and conflict continued to plague the city. In 1968, ten days before it was to host the Summer Olympics, 200-300 students and protestors were killed by the Mexican military in what came to be known as the Tlatelolco Massacre. In 1985, an earthquake that measured 8.1 on the Richter scale destroyed much of the city and left thousands dead.
Today, Mexico City continues to grow and is an economic and cultural center of Latin America. In 2003, the Torre Mayor building was completed in Mexico City, making it the tallest skyscraper in Latin America (755 feet).