What is the white building pictured in the San Francisco (21043) set?
I believe it is 50 Fremont Center/Salesforce West Tower (it's right in front of/besides Salesforce Tower);


I acknowledge that the scale seems off. I'm guessing it is the Fremont Center based on it's location, appearance, and that Lego didn't bother labeling it, as if Salesforce West is part of Salesforce Tower. Also, if you were to look at Salesforce Tower from Coit Tower, the white buildings position is pretty much right on (if other buildings weren't blocking your view).
  Additionally, none of the landmarks or their proximity to each other are really on scale in this Lego set.  I feel like it's more of a representation than a model.