The Plaza de las Tres Culturas is so named because it symbolizes the fusion of pre-Hispanic and Spanish roots into the Mexican mestizo identity. It displays the architectural legacy of those three cultural strands: the Aztec pyramids of Tlatelolco, the 17th-century Spanish Templo de Santiago and the modern Secretaría de Relaciones Exteriores (Foreign Ministry).

The Plaza of Three Cultures is a calm oasis in the city, but is haunted by the echoes of its sombre history. Founded by Aztecs in the 14th century, Tlatelolco was a separate dynasty from Tenochtitlán, on a separate island in Lago de Texcoco. Cortés defeated Tlatelolco's Aztec defenders here in 1521. You can view the remains of Tlatelolco's main pyramid-temple and other Aztec buildings from a walkway around them. The Spanish, recognizing the religious significance of the place, built a monastery here and then, in 1609, the Templo de Santiago.

Tlatelolco is also a symbol of more modern troubles; it was where government troops massacred hundreds of protesters on the eve of the 1968 Mexico City Olympic Games. The full truth about the massacre has never come out: the traces were hastily cleaned away, and Mexican schoolbooks still do not refer to it.