A grand opening advert for the WESTGATE Gilchrist's, which made its debut in October 1963. The store's most noteworthy feature was its 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 356,000 leasable square feet and was anchored by the aforementioned Gilchrist's and a Bradlees Family Center. There was free parking 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)