I'm not too sure about this one. They're mostly nondescript office buildings (okay, one has apartments) which I checked out after the Democratic convention. There are three of them right next to the Harold Washington Library at the south end of the fabled loop. 

I can understand why much of the architecture of Chicago would be considered WHS-worthy, but aside from the age, there's not any reason for these buildings over any of the others there. The city has so much great architecture that the choice is a mystery. Also, all of these are private and the owners want to demolish them and build the best of what architects have to offer. 

Worth the visit if you are there on other business.