After an apprenticeship with furniture designer Bruno Paul, Ludwig Mies van der Rohe joined the office of Peter Behrens, where he began to develop his architectural practice. As a member of the Deutscher Werkbund, he took part in the lively cultural and architectural debate of his time and, after WWI, increasingly devoted himself to visionary projects, drawings and theoretical studies. His 1919 project for the Friedrichstrasse skyscraper and the subsequent studies for a glass skyscraper introduced a new conception of architecture based on structure, transparency and space. In 1927, together with some of the leading modernist architects of the time, he designed the Werkbund Exhibition at the Weissenhof Estate in Stuttgart, considered a landmark in the development of the International Style. This was followed by the German Pavilion in Barcelona and Villa Tugendhat in Brno, both completed in 1929. As Director of the Bauhaus from 1930, he continued to promote a rigorous and integrated approach to architecture, design and technology. After his involvement with the avant-garde magazine G: Material zur elementaren Gestaltung and the architectural group Der Ring, he moved to the United States in 1938 to direct the Department of Architecture at the Armour Institute of Technology in Chicago, becoming a central figure of the Second Chicago School.