A grand opening advert for the WESTGATE Gilchrist's, which made its debut in October 1963. The store included a Bargain Basement Annex.
Advert from Gilchrist's Department Stores

WESTGATE SHOPPERS' PARK was the Bay State's first fully-enclosed shopping mall. The 3 million dollar complex encompassed approximately 356,000 leasable square feet, It was anchored by the aforementioned Gilchrist's and a Bradlees Family Center. Free parking was provided for 3,000 autos.

A vintage interior view of the WESTGATE mall. Jordan Marsh assumed a vacant Gilchrist's store in mid-1977. A Kennedy's store appears on the right.  

Photo from The Enterprise (Brockton, Massachusetts)