Le Corbusier also contributed two designs, one a single-family in reinforced two design, one a single-family in reinforced concrete and the other duplex with a steel frame, a realization of the Citrihan concept. the latter was one of the most controversial structures and the exhibition, in past because of its unorthodox interior proportions. the main circulation spine is a corridor that runs the length of the house with dimensions and window that suggested a train more than a residence, particularly as some bedrooms were narrow, like the sleeping compartments of European trains. Le Corbusier was, in fact, fascinated by the functional designs of ocean-liners and airplanes, so it is possible that railway cars also inspired his architecture.