Is the modern city of Mexico City where Aztecs lived?

Yes, Mexico City is built on the ruins of the ancient Aztec city of Tenochtitlan, which was the capital of the Aztec Empire. Tenochtitlan was founded in 1325 and was one of the largest and most powerful cities in the pre-Columbian Americas. It was conquered by the Spanish in 1521 and the Spanish built Mexico City on its ruins.