Louis Sullivan (1856-1924) began his career as an architect in Philadelphia, then moved to Chicago in 1873 when the city was rebuilding after the Great Fire. At the time “tall buildings” were at most about sixteen stories high and were supported by heavy masonry walls. Between Burnham and Root’s seventeen-story Monadnock building and the twenty-six-story towers of Mies van der Rohe in the 1950s, there was only Sullivan. He took the concept of the metal-frame structure and saw in it the lightness and economy it could produce. He was also famous for his art nouveau ornamentation.
