Mexico City () is the capital and largest city of Mexico. It is also one of the most populous and polluted cities in the world. The Aztec people were here before the Spanish came and made Mexico City. It was founded in 1521 by Hernán Cortés. Today, about 8.5 million people live in the city, and about 18 million live in the Greater Mexico City urban area. The city of Mexico City ceased to exist in 1928. Since then, there is only the Federal District.