Plaza is a Spanish word related to "field" which describes an open public space in a city, such as a city square. In Spanish America, the plaza mayor of each city had three things: the cathedral, the cabildo or administrative center, and the audiencia or law court. The plaza might be large enough to serve as a military parade ground. At times of crisis or fiesta, it was a space where many people could be together at once. Similar to Italian piazzas, plazas are still a center of community life, like the market-place.
Most colonial cities in Spanish America were planned around a square plaza de armas, where troops could gather.
A plaza de toros is a bullring.
The first shopping center in the United States, opened in Kansas City, Missouri in 1922, was called "Country Club Plaza" and had Spanish-style architectural details. More recently, plaza has been used to describe a shopping center, similar to a shopping mall. Calling a shopping center a plaza is to give the idea of a center of cultural life.