Mexico City was built upon the Aztec capital of Tenochtitlán. When the Spanish conquered the Aztecs they tore down the buildings of Tenochtitlán and used those stones to build their new capital of the Viceroyalty of New Spain. But if you dig below the surface of Mexico City's historic center, the foundations of the Aztec city are still to be found, not to mention an archaelogical treasure trove of pre-Hispanic artifacts. The most famous example is the base of the Templo Mayor (Main Temple) which was excavated after utility workers digging under a downtown street came upon a large Aztec carving in 1978.
Since then more and more has been found beneath the city. In 2002 the Spanish government acquired a colonial mansion that had been damaged in the 1985 earthquake. They restored the structure and opened it as the Cultural Center of Spain. In 2012 a new wing was added to the building on an empty lot that had been used as a parking lot. During construction, Aztec ruins were found beneath the lot. Archaeologists believe that the ruins are the remains of the "calmecac", the school for the sons of Aztec nobles. Now you can go down into the basement of the Cultural Center and see this excavation as well as cases displaying artifacts that were found on the site.
This painted image is of Ehecatl, the Aztec god of wind.
This carving shows a dismembered human leg, perhaps a reference to the fact that in some sacrificial rituals the victim's body would be dismembered after sacrifice.
This architectural decoration, known as an "almena", would have adorned the roof of the building. It somehow survived intact.
Fragments of Aztec pottery with the painted decoration still clearly visible...
Artefacts from the Spanish colonial era were also found, such as this fragment of a crucifix.
Although the excavation is not especially large or impressive, it is a fascinating reminder of the other city that lies below Mexico's capital.