Above the two storefronts at 1520-22 N. Milwaukee Avenue in Wicker Park reads "The Peoples Gas Light & Coke Company."
This company wasn't exactly "forgotten;" they are the precursor to today's Peoples Gas. They were Chicago's first utility company - Chicago Gas Light Coke Company - in 1849 and became The Peoples Gas Light & Coke Company in 1895 following a merger with a dozen different gas companies. In this case, of course, the coke meant fuel, not the drink or the drug.
The building itself was designed in 1921 by Jens J. Meldahl in a Classical Revival style, with the facade redesigned by Herman Von Holst a few years later. A photo of how the building appeared in 1923 (in detail) can be found here. As you can see, it is remarkably similar to how it originally appeared 90 years ago.
The building is a contributing factor of the designation of the Milwaukee Avenue District in Wicker Park as a Chicago Landmark.