The Aztecs lived in Mexico and extended into Central America. Their capital city was Tenochtitlan, built on islands in Lake Texcoco. Their empire covered over 80,000 square miles and used causeways and aqueducts to transport materials and fresh water into the capital city. The Aztecs originated from a northern hunter-gatherer tribe and settled on the islands of Lake Texcoco after seeing an eagle perched on a cactus, which they took as an auspicious sign.