Westminster 5 Theatres

Many of AMCs 6-plexes of the era were built with ground floor projection booths using mirrors, usually three separate booths each serving two screens.

I’ve always been curious about this theater because it looks like it was originally built as a twin and had another building added on to it. To see that AMC opened it as a 5-plex is even more curious to me. Did they build it this way? Did they convert an existing building?