Bigelow has found out that it was Halliday who had poisoned him and rushes to his office in the Bradbury Building (described earlier here) to confront him.
Below, he looks up and sees that Halliday's office lights are still on (click image to enlarge).
Then ... As he makes his way across the street we see those same windows lit up but, hang on, this is not the Bradbury Building ... it's actually the Million Dollar Building (that's the Million Dollar Theater in front) at 307 Broadway and 3rd Street, directly opposite the Bradbury Building (map).
... and Now, the Million Dollar Building as it is today (below). The theater is still in business, catering to a Spanish-speaking audience, but the offices above it were recently converted to residential units.
Then ... But as he enters the building ...
... and Now ... we see that this really is the Bradbury Building, at the 3rd Street entrance near the corner of Broadway (map). Note the external fire pipe down the right side of the entrance - still there after more than 60 years!
Then ... Halliday, in the same overcoat he wore when he doctored Bigelow's drink in San Francisco, leaves his Bradbury office just as Bigelow approaches on the 3rd floor balcony (take a moment and savor the dramatic shadows of the railing projected across the balcony floor. Isn't noir wonderful?).
... a similar view ... this undated photo captured a very similar view.
Then ... In the ensuing exchange of gunfire Bigelow prevails, finally achieving the redemption of a punitive but successful end to his last furious hours.
... and Now, the same view today looks as it always did, testament to the lasting legacy of a classic building, incidentally designed not by a trained architect but by a draftsman who worked for Lewis Bradbury.
The movie ends as it starts, at the homicide department where the rapt officers have been hanging on to every word of Bigelow's incredible tale. His final word is "...P-Paula ..." then he drops to the ground.
"How shall I make out the report on him, Captain?"
"Better make it - Dead On Arrival"