August Roterberg's magic shop was located here in 1893. This location was verified by William Pack in a Chicago Tribune classified ad. Dai Vernon, as a kid, mail ordered his magic from Roterberg. Roterberg was also advertising at this location in early 1895. But by August of 1895 he was using a new address.
As Roterberg emigrated to the U.S. as a teenager about 1883, this is believed to be the first outside of his home.
This was 26 N. Clark, before the street renumbering. This might also be the same location as 26 N Class St, an address Roterberg also used.
This location is not mentioned in the Roterberg timeline given by Felsman (Felsman's Magical Review. Vol 1. No 6. 1920).
Link: August Roterberg at MagicPedia.Roterberg's Magic Shop