(Bob used clues in the text to narrow down the likely location of Spenser's apartment, and went there to take pictures. Unfortunately the pictures are gone, but his notes allow us to identify the apartment anyway.)
We always knew that Spenser lived on Marlborough Street, somewhere near the Arlington Street end by the Public Garden. Here is its counterpart in the real world. My reasoning (such as it is):
- In Looking for Rachel Wallace Foley gives Spenser and Rachel a ride back from the English house.
- "He pulled into Marlborough Street from Arlington and went up it the wrong way two doors to my apartment."
- Since then the traffic pattern has changed. Marlborough is one way heading east for most of its length but the residents of the last block got sick of people using the street as a throughway and that block is now one way west to Berkeley Street. I got that info from a local resident.
- In God Save the Child Spenser gave Susan directions to his apartment.
- "I'm on the last block before you get to the Public Garden... it's on the left hand side."
- Noting the traffic direction from above that puts him on the north side of the street.
- He must be on that block anyway. When leaving his office Spenser always walks one block east to Arlington, north to Marlborough, and enters the street from that end. If he were further down he would walk up Berkeley to Marlborough and take a left.
- Why not just walk up Berkley and take a right? From personal experience I can tell you it's much more pleasant to stroll by the Public Garden going from one location to the other.
- In Walking Shadow ch. 22 we have two more clues to nail it down
- "There was the fire escape, which came down into the public alley between Marlboro (sic) and Beacon Street."
- Bingo: Beacon is the next street north so we are dealing with Public Alley 421.
- The closeness to the corner plays a crucial role:
- "Then I hotfooted it down the front stairs and out the front door. I went down Marlboro (sic) Street on the dead run...turned the corner on Arlington Street, past one building and into the alley that ran behind my building...if it had worked they should be on the fire escape."
I'm not saying it's perfect. Elsewhere in Walking Shadow ch. 22 he notes the elevator going up to the sixth floor, and as you can see the building is not quite that tall. Also, there is no fire escape leading to the alley behind the above building. Oh well, that's fiction for you.
(For the 'big picture', see Spenser in Context.)