Frank Lloyd Wright (1867- 1959) University of Wisconsin (school of engineering), he left without finishing, 1887 Chicago, 1893 set up his own practice. Organic architecture: inspired by nature, buildings seem to grow naturally, aim-> create harmony between buildings and natural world. The architect has to take into consideration the characteristics of the site: Prairie period (Robie House: horizontal orientation of the building, put internal and exterior areas in contact, limited numbers of dividing walls, natural materials, no decorative elements) Usonian period -private residences meant for the middle class - ( The Waterfall Residence) - The Guggenheim Museum N.Y.