Valley Fair opened in 1956 with 39 stores around a central Macy’s, on the San Jose side of today’s mall. The Macy’s was built so it could later grow upward, and for its first two years its roof held a children’s carnival. Historian Heather David calls Valley Fair the South Bay’s first modern suburban shopping mall; it offered fashion shows, air-conditioned stores and parking for more than 3,000 cars.
Wikipedia gives the opening year of the original center as 1958, but the Pacific Coast Architecture Database, History San Jose and the Sourisseau Academy all date Macy’s and Valley Fair to 1956.