The Aztecs were guided to settle on an island in a lake after seeing an eagle perched on a cactus, fulfilling a prophecy. They built their city of Tenochtitlan there, which now lies at the center of Mexico City. The Aztecs had several creation myths to explain the origins of the world and humanity. After the Spanish conquest, Cortes initially maintained Aztec rule but replaced the nobility with Spanish landowners, establishing an oppressive system of forced native labor on silver mines that contributed greatly to Spain's wealth for hundreds of years. The Aztec education system was abolished and aspects of their culture were forbidden, contributing to the civilization's decline under Spanish rule.