The nucleus of the Aztec Empire was the Valley of Mexico, where their capital Tenochtitlan was built upon raised islets in Lake Texcoco. After the 1521 conquest of Tenochtitlan by Spanish forces and their allies which brought about the effective end of Aztec dominion, the Spanish founded the new settlement of Mexico City on the site of the now-ruined Aztec capital. The capital of the modern-day nation of Mexico, the greater metropolitan area of Mexico City now covers much of the Valley of Mexico and the now-drained Lake of Texcoco.
Aztec culture had rich and complex mythological and religious traditions. For Europeans, the most striking element of the Aztec culture was the practice of human sacrifice which was conducted throughout Mesoamerica prior to the Spanish conquest.
The Aztecs spoke Classical Nahuatl. Although some contemporary Nahuatl speakers identify themselves as Aztecs, the word is normally only used as a historical term referring to the empire of the Mexicas, as distinguished from the Mexicas alone. This article deals with the historical Aztec civilization, not with modern-day Nahuatl speakers.