Barrios of pre-conquest Tlatelolco over modern map
In 1337, thirteen years after the foundation of Tenochtitlan, the Tlatelolca declared themselves independent from the Tenochca and inaugurated their first independent tlatoani (dynastic ruler). Under the king Cuacuauhpitzahuac (1376–1417), the first two stages of the Main Pyramid of Tlatelolco were constructed. Under Tlacateotl, the Tlatelolca assisted the Tenochca in the war against the Tepanec empire, dominated by Azcapotzalco. shortly thereafter, the first war between the Tenochca and Tlatelolca erupted. Also during Tlacateotl's reign, the third stage of the Main Pyramid was constructed. Under Cuauhtlatoa (1427–1467), the Tlatelolca conquered the city-state of Ahuilizapan (now Orizaba, Veracruz), and fought against the people of Chalco along with the Tenochca. The fourth and fifth stages of the Main Pyramid were constructed in this period. The ruler Moquihuix constructed the sixth stage of the temple, but in 1473 he was defeated by the Tenochca tlatoani Axayacatl, and Tlatelolco was made subject to Tenochtitlan. Itzcuauhtzin ruled Tlatelolco during a period in which it was almost completely incorporated into Tenochtitlan.:65
After the completion of the two-year Spanish Conquest of the Aztec Empire in 1521, the Spanish conquerors established the ruins of Mexico-Tenochtitlan as the Spanish capital of New Spain. The remnants of the indigenous populations of Tenochtitlan and Tlatelolco following the conquest were administered by indigenous elites in the incorporated Indian towns of Santiago Tlatelolco and San Juan Tenochtitlan. Tlatelolco remained an important location in the colonial era, partly because of the foundation there of the school for elite indigenous men, the Colegio de Santa Cruz de Tlatelolco, which was the first school of higher learning in the Americas. Today its remains are located within Mexico City.
In the twentieth and twenty-first centuries, archeological excavations have taken place at the Tlatelolco (archaeological site) in what is now part of Mexico City. The excavations of the prehispanic city-state are centered on the Plaza de las Tres Culturas, a square surrounded on three sides by an excavated Aztec site, a 17th-century church called Templo de Santiago, and the modern office complex of the Mexican foreign ministry. In February 2009, the discovery of a mass grave with 49 human bodies was announced by archaeologists. The grave is considered unusual because the bodies are laid out in ritual fashion.