Louis Henri Sullivan is definitely the father of modern architecture. His particular style is characterized by a simplification of form, while the ornamental details are given by the structure and the theme of the building. Sullivan is considered the creator of the modern skyscraper, due to its participation to the construction boom in Chicago that followed the Great Fire of 1871.
Louis Sullivan was one of the first architects at his time to embrace the column-frame construction technique, which allowed taller buildings with larger windows to be erected. This method used steel girders, suspended from the walls, floors and ceilings in order to carry all the weight of the building. He was hired by Dankmar Adler in 1879, with whom he designed famous structures like: The Auditorium Building in Chicago, Wainwright Building in St. Louis and Prudential Building in Buffalo, New York.
The Auditorium Building is one of his best-known designs and it was first the home for the Chicago Civic Opera and Chicago Symphony Orchestra. Nowadays it stands a national historic landmark. His individual works include The Sullivan Center (formerly known as Carson, Pirie, Scott and Company Building) in Chicago, the Bayard-Condict Building in New York City and the Krause Music Store in Chicago. All of his personal structures were enriched with Art Nouveau details. Through Louis Sullivan, the Art Nouveau style originally emerged in Belgium crossed not only borders, but oceans too.