Tenochtitlan
According to a traditional story, the Mexica wandered in the deserts of modern Mexico for 100 years before they came to the thick forests of the place now called the Valley of Mexico.
Tenochtitlan was founded on an islet in the western part of the lake in the year 1325. Around it, the Aztecs created a large artificial island using a system similar to the creation of chinampas. To overcome the problems of drinking water, the Aztecs built a system of dams to separate the salty waters of the lake from the rain water of the effluents. It also permitted them to control the level of the lake. The city also had an inner system of channels that helped to control the water.
During Cortés's siege of Tenochtitlan, the dams were destroyed, and never rebuilt, so flooding became a big problem for the new Mexico City built over Tenochtitlan.
Read more about this topic: Lake Texcoco