Final answer:
After defeating the Teponecs, the Aztecs faced the Spanish conquistador Hernán Cortés, who destroyed Tenochtitlan and built what is now Mexico City.
Step-by-step explanation:
After defeating the Teponecs, the Aztecs faced the Spanish conquistador Hernán Cortés, who proceeded to execute Moctezuma, level Tenochtitlan, and begin to build what is now Mexico City. The destruction of Tenochtitlan was so thorough that very few Aztec ruins remain today.