You beat me to it by seconds,
Beaudry!
There seem to be quite a few images showing the area around the western end of the Third Street tunnel/Hope Street and the Alta Vista. I've marked my guess for the location of the building with the X on the 1955 image below. It's on the sloped road that runs parallel to Hope Street joining Third Street to Second Street. The Alta Vista is the white building on Bunker Hill Avenue in the lower left corner. I think that the windows of the large white building on Cinnabar Street match the building in the background of the mystery photo.
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