A 1970s exterior view shows one of the five color-coded mall entrances. This is, obviously, the "Red Entrance" which provides access to the center section of the complex. Off in the distance is the Diamond's anchor store.
Photo from Westcor, Incorporated

Apparently, METROCENTER did not have any type of formal, mall-wide Grand Opening celebration. Stores commenced operation between October 1973 and December 1974. In lieu of an official dedication, a "Salute To Arizona" fair had been held in April 1974. Sears and forty-nine inline stores were launched. With their completion, the mall housed a total of 115.