As the global Great Depression enveloped Europe, Le Corbusier devoted more and more time to his ideas for urban design and planned cities. He believed that his new, modern architectural forms would provide an organizational solution that would raise the quality of life for the working classes. In 1922 he had presented his model of the Ville Contemporaine, a city of three million inhabitants, at the Salon d'Automne in Paris. His plan featured tall office towers with surrounded by lower residential blocks in a park setting. He reported that "analysis leads to such dimensions, to such a new scale, and to such the creation of an urban organism so different from those that exist, that it that the mind can hardly imagine it." The Ville Contemporaine, presenting an imaginary city in an imaginary location, did not attract the attention that Le Corbusier wanted. For his next proposal, the Plan Voisin (1925), he took a much more provocative approach; he proposed to demolish a large part of central Paris and to replace it with a group of sixty-story cruciform office towers surrounded by parkland. This idea shocked most viewers, as it was certainly intended to do. The plan included a multi-level transportation hub that included depots for buses and trains, as well as highway intersections, and an airport. Le Corbusier had the fanciful notion that commercial airliners would land between the huge skyscrapers. He segregated pedestrian circulation paths from the roadways and created an elaborate road network. Groups of lower-rise zigzag apartment blocks, set back from the street, were interspersed among the office towers. Le Corbusier wrote: "The center of Paris, currently threatened with death, threatened by exodus, is in reality a diamond mine...To abandon the center of Paris to its fate is to desert in face of the enemy."