Tenochtitlan, also known as Mexico-Tenochtitlan, was a large Mexican altepetl in what is now the historic center of Mexico City. The exact date of the founding of the city is unclear, but the date 13 March 1325 was chosen in 1925 to celebrate the 600th anniversary of the city. The city was built on an island in what was then Lake Texcoco in the Valley of Mexico. The city was the capital of the expanding Aztec Empire in the 15th century until it was captured by the Tlaxcaltec and the Spanish in 1521.

The altepetl was the local, ethnically-based political entity, usually translated into English as "city-state," of pre-Columbian Nahuatl-speaking societies in the Americas. The altepetl was constituted of smaller units known as calpolli and was typically led by a single dynastic ruler known as a tlatoani, although examples of shared rule between up to five rulers are known. Each altepetl had its own jurisdiction, origin story, and served as the center of Indigenous identity. Residents referred to themselves by the name of their altepetl rather than, for instance, as "Mexicas." "Altepetl" was a polyvalent term rooting the social and political order in the creative powers of a sacred mountain that contained the ancestors, seeds and life-giving forces of the community. The word is a combination of the Nahuatl words ātl and tepētl. A characteristic Nahua mode was to imagine the totality of the people of a region or of the world as a collection of altepetl units and to speak of them on those terms. The concept is comparable to Maya cah and Mixtec ñuu. Altepeme formed a vast complex network which predated and outlasted larger empires, such as the Aztec and Tarascan state.