The original Springfield, Illinois, Carnegie public library (1904 - 1975, RIP) had frosted glass floors up in the stacks. Once a person got used to standing, sometimes sitting, on glass, it was comforting. I still have dreams about the building.
📷 Lincoln Library
I have been inside 129 Illinois public libraries and don’t think I’ve ever seen anything like this in Sterling: three-story stacks with glass floors to let in more light, original to the 1904 Carnegie building.