Fleur de lis pattern.  From the Daughters of Isabella Building in Chicago, one of the first buildings designed by the architectural partnership of Jenney and Mundie.  SeeThe Doorknob Collector#17 (photo below).  The first floor hardware was cast of aluminum and the other floors were made of brass using a custom plate and related hardware that later became Yale's Cologne design, using a different doorknob. Click on each photo below to view additional images and information