Very interesting, albeit now I'm really salivating, as beside *evidently* the second floor not yet added, (edit: In fact it appears it is upon intense study) there appears to be some other structure previously not been discussed, at least with me. Shadows due to the angle of light can cast misleading detail. I'm forwarding this to the lead architect who knows the building concerned (and those adjacent) intimately. It *appears* that some of the claim for the amount of 'glass' on the building may be out of proportion. It might be that the 'panels' engineered into the building facade were just modular for bricks as well as windows, but that observation is subjective until I can get greater detail.Here's a 1920 aerial of the area that interests you:
Many thanks for that Goldie!