A district of Tenochtitlan and home of the Plaza de Tres Culturas (Plaza of Three Cultures). (Nahuatl word; pronounced Tlah-teh-lohl-koh) Originally a separate town, Tlatelolco became a district of Tenochtitlan in the 1400s. The Spaniards overcame the last Aztec defenders here in 1521. The Plaza of Three Cultures includes the early Indian ruins, a colonial church, and modern public housing projects symbolizing Mexico's historical trajectory. The plaza was the site of one of modern Mexico's most appalling tragedies: the massacre of October 2nd, 1968 in which approximately 300 students were killed by the army during a large protest against President Díaz-Ordaz.