Conservatory.  

The Lutheran Brotherhood building, built in 1953, was generally unloved until its execution was announced - then everyone suddenly realized how virtuous a structure it was. After 20 years of big bland buildings, something this clean and modest suddenly looked refreshing. But it was doomed; the floors were too small for high-buck tenants, and more money could be made building a new structure on the site.

As an example of International Style architecture, it's ambivalent - the facade is clean and cerebral, but they couldn't resust sheathing the bottom floor in stone. No matter - it was a modest little gem, a human-scaled version of its monstrous New York brethern. Lutheran Brotherhood (an insurance company) abandoned this home for a bizarre, cash-register-shaped building in the 80s; it was then occupied by a local utility firm. It was demolished in the summer of 1997.