The Chicago Style, Chicago Commercial, Commercial style, and Chicago School describe architecture that originated with architects in Chicago in the late 19th and early 20th centuries. It featured the use of steel and larger window openings than previous masonry construction allowed. The Chicago window emerged with a wide central fixed plate glass window, flanked by narrower windows with movable sashes on either side. The Chicago School of Architecture included leading group of pioneer skyscraper architects led by William Le Baron Jenney (1832-1907) that also included Louis Sullivan (1856-1924), John Wellborn Root (1850-1891), and others. Also see Second Chicago School.