of the Congres Internationaux d'Architecture Moderne (CIAM), attending the second congress in Frankfurt in 1929 and the fourth congress in Athens in 1933, where he established a close friendship with László Moholy-Nagy, Sigfried Giedion, and Philip Morton Shand. It was during this time that he closely followed the work of the main force driving the new modernism, Le Corbusier, visiting him in his Paris office several times in the following years. It was not until the completion of the Paimio Sanatorium (1932) and Viipuri Library (1935) that Aalto first achieved world attention in architecture. His reputation grew in the US following the invitation to hold a retrospective exhibition of his works at MOMA in New York in 1938. (This was his first visit to the States.) The exhibition, which later went on a 12-city tour of the country, was a landmark: Aalto was the second-ever architect – after Le Corbusier – to have a solo exhibition at the museum. His reputation grew in the US following the critical reception of his design for the Finnish Pavilion at the 1939 New York World's Fair, described by Frank Lloyd Wright as a "work of genius". It could be said that Aalto's international reputation was sealed with his inclusion in the second edition of Sigfried Giedion's influential book on Modernist architecture, Space, Time, and Architecture: The growth of a new tradition (1949), in which Aalto received more attention than any other Modernist architect, including Le Corbusier. In his analysis of Aalto, Giedion gave primacy to qualities that depart from direct functionality, such as mood, atmosphere, intensity of life, and even national characteristics, declaring that "Finland is with Aalto wherever he goes." Mid career: experimentation During the 1930s Alvar spent some time experimenting with laminated wood, sculpture and abstract relief, characterized by irregular curved forms. Utilizing this knowledge, he was able to solve technical problems concerning the flexibility of wood while at the same time working out spatial issues in his designs. Aalto's early experiments with wood and his move away from a purist modernism would be tested in built form with the commission to design Villa Mairea (1939) in Noormarkku, the luxury home of young industrialist couple Harry and Maire Gullichsen. It was Maire Gullichsen who acted as the main client, and she worked closely not only with Alvar but also with Aino Aalto on the design, encouraging them to be more daring