The first structure built at the HILLSDALE site was an Andrew Williams Store grocery, which opened in January 1942. It was expanded -and rebranded- as a Mayfair Market in 1951. Here we see said store decked out for the yuletide season.
Photo from

A freestanding Sears was the second operational building at the mall site. This Late Moderne-style store was dedicated in March 1951.
Photo from "Shopping Can Be Fun" video / George H. Kelley

Construction got underway on the HILLSDALE CENTER mall in December 1953, with an official dedication held in November 1954. Here we see the South Wing of the original open-air complex.
Photo from

Macy's California dedicated a 155,000 square foot store as part of the grand opening of HILLSDALE CENTER. It was the very first shopping mall-format Macy's operation in the nation.