Tenochtitlan, capital of the Aztec Triple Alliance. One of the most advanced cities in the world, it was built upon lake Texcoco. Outside the ceremonial downtown were vast markets and neighborhoods of houses navigated by water channels. It had a population of up to a million people and, unlike European cities, was pristine and hygienic. This blessing would prove a curse as Eurasian disease destroyed the Aztecs. Approx 1500 AD. Artist unknown.