Before there was the Arcade Building, there was the obscure, bizarre, short-lived Fagin Building:
A. W. Fagin Building
This page, by a distant relative of the building's architect, offers some detailed views and interesting commentary. The Fagin Building showed a use of bold forms similar to those of Frank Furness (and similarly reviled in the architectural press of the time); its facade contained vast areas of glass to allow natural light to flood the interior -- a Modernist tenet decades ahead of its time. It was remodeled into the far less interesting Burlington Building after only a few years, but for that short time St. Louis had a truly remarkable gem of architecture.