Per Wikipedia:
The Wesley Bolin Memorial Plaza is an urban park and gathering place, located in front of the Arizona state capitol complex in downtown Phoenix, Arizona. It serves as a home to a number of memorials honoring prominent figures in Arizona history as well as memorializing significant wars and other events that have had an impact on the state. It is designated as one of the Phoenix Points of Pride.
The plaza was established on March 9, 1978, by the Arizona Legislature in honor of Governor Wesley Bolin, who had died a mere 5 days previously on March 4. Prior to the resolution creating the plaza, it had simply been a part of the Legislative Governmental Mall. While the plaza exists only as a part of the Mall, in common usage the terms are interchangeable and the name of the plaza is often used in preference to the Mall.
Much like the National Mall on which it is loosely based, the Legislative Governmental Mall is intended as an open-air public space featuring monuments, memorials and gardens. Some of these monuments were erected prior to the inception of the Plaza, such as the monument to the USS Arizona which was dedicated over a year earlier on December 7, 1976. The Plaza, when dedicated, included these existing memorials and all subsequent memorials have been located within the boundaries of the plaza.
Owing to its location directly in front of the state capitol, the plaza has also become a meeting place and a focal point for protests and demonstrations, such as the 2006 United States immigration reform protests, with Phoenix participants culminating in a rally at the plaza. Over 100,000 participants took part in the display.