In 1926 and 1927, Le Corbusier developed a set of architectural principles for modern architecture. He advocated five points of modern architecture: pilotis, the roof garden, free plan, and free façade, and the horizontal window. By making the frame structure independent of the exterior walls, it became possible to run windows horizontally along the façade for unobstructed views to the outside and evenly distributed natural light inside the building. The Pros and Cons of the Horizontal Window. The Perret- Le Corbusier Controversy (1984) by Bruno Reichlin is the authoritative publication on horizontal windows.