Elevator to Sam Spade's office?

A lot of folks think Dashiell Hammett had the Hunter-Dulin Building in mind as the location of Sam Spade's office. The owners of the building lay claim to this distinction with a display by one of the entrances that says, "Traced to historic 111 Sutter Street by following directions and clues woven through his novel . . . Sam Spade remains in residence at his 'office at Sutter and Montgomery.'" 

It's possible. Construction on the building began in 1925 and was completed in 1927. Hammett's novel, The Maltese Falcon, was published in 1930.  

To be sure, I would want to look for the "directions and clues" in the novel, and I would like to find out what buildings occupied the other three corners at Sutter and Montgomery in the late-1920s. I'm not sure when I'll get around to those tasks. 

​Meanwhile, I keep in mind an observation by my friend, Gloria Lenhardt. The lobby of the building is luxuriously appointed with several kinds of marble and brass elevator doors. Did Spade and Archer attract high-end clients whose fees would pay rent in a posh new building? That seems doubtful, but maybe Hammett was trying to reflect some glamor on his private eye.