Mexico City was first built in the 1520s after Hernán Cortés destroyed the Aztec city of Tenochtitlan. The Spaniards then emptied the basin of Lake Texcoco to keep it from flooding. By the late 1700s, Mexico City had over 100,000 people. However, there were many slums, which caused epidemics. There were political problems in the mid 1800s after Mexico became independent. More than 40 people ruled in the 40 years after the country became independent. In the late 1800s and early 1900s, electric light and gas were brought to the city. But there was a big difference between the rich western part of the city and the poor eastern part of the city. By 1930, Mexico City had 1,000,000 people. The city kept growing quickly. In 1968, the Olympic Games were in Mexico City. In 1985, an earthquake hit the capital. In the past few decades, there have been problems with crime and corruption.