Tenochtitlan is located in the Federal District in Mexico and was built on an island in Lake Texcoco. The capital of Mexico is built on top of the ruins of Tenochtitlan, but many ancient structures from the original city still exist. The city of Tenochtitlan was founded in 1325. According to Aztec legend, this region was chosen based on an ancient prophecy that stated that the Aztec capital would be built where the people saw an eagle eating a snake while sitting on a cactus. At its height, the city of Tenochtitlan was home to almost 250,000 people and covered around thirteen square kilometers. The city was divided into four zones, each with twenty districts, with public buildings such as temples and schools located in the city center. The palace of Montezuma, the fifth emperor of the Aztec Empire, was also located in the central area of Tenochtitlan and contained zoos, botanical gardens, and aquariums of both salt and fresh water.