Modern architecture emerged in the early 20th century as architects experimented with new materials and techniques. Key figures included Le Corbusier who developed principles like pilotis and long ribbons of windows. Frank Lloyd Wright developed the Prairie Style seen in buildings like Fallingwater. Louis Sullivan pioneered skyscrapers like the Wainwright Building, expressing the steel structure on the exterior. The Bauhaus school and figures like Mies van der Rohe promoted functionalism using steel and glass. By mid-century, Modernism was criticized for sterility and new movements like Brutalism emerged.