Plenty of people guessed that it was a location in Roxbury because of the puddingstone wall and the elevated rail tracks under construction. But what made this one particularly tough was that the building in back hasn't been there since the 1930s, when it was demolished to make room for the "new" Bartlett Yard bus garages. Judging by the unfinished elevated railway platform, this photo dates from about 1908.
That building in back - the old Bartlett Carhouse - can be better seen in this photo from about the same era. It was located right on the corner of Guild Street and Washington. In the lower photo, there is a clearly visible spur of the elevated railroad running behind the carhouse. That spur led to the repair facility which ran along Guild Street. That's why there is a huge puddingstone wall in Bartlett Yard - it had to support the weight of several elevated trains.
Today all that's left is the jungle behind the chain link fence on Guild. In the not-too-distant future, there will be houses on both sides of Guild as that site is developed.