Plaza dela Constitucion was built by the Spaniards on the site of the main temple complex of TENOCHTITLAN, the capital of the Aztec Empire. This enormous paved square, the largest in the Western Hemisphere, was built by the Indian slave labor on the site of the Aztec ceremonial center, which once comprised 78 buildings. There is an air of old Europe to this section of the city, which, in its entirety (the Centro Historico), is a national monument.

Throughout 16th, 17th and 18th centuries, the Spaniards and their descendants constructed in this area some of the more elaborate churches and convents, elegant mansions and stately public edifices, of which many has been converted to other uses. Throngs of small shops, eateries, cantinas and street vendors contribute to an inimitably Mexican exuberance and flavor.

ZOCALO means "pedestal" or "base". In the 19th century, an Independence monument was envisioned for the square, but it was never built. The term stuck, however, and now the word zocalo is applied to the main plazas of most Mexican cities. Mexico City's Zocalo(since it is the original, it is always capitalized) is used for government rallies and festive events.