Hangars pour dirigeable, Orly

In publishing photographs of their construction in L’Esprit nouveau, Le Corbusier revealed the technical achievement and the visual and spatial qualities that made the Orly airship hangars a twentieth-century masterpiece. These were built between 1921 and 1923 by engineer Eugène Freyssinet, pioneer of prestressed concrete. The envelope consisted of 40 parabolic arches, trough-like in section, 7.50 m in width and 86 m in span, the depth in section tapering from 5.40 m at the base to 3 m at the top, the concrete skin no more than 9 mm at its thinnest. The arches rested on a metre-thick concrete slab set in the ground two metres beneath floor level. The method of construction was decisive for the choice of form: concrete was solid for weathertightness, yet fluid and rapid-setting, allowing the reuse of moulds; rail-mounted wooden centering could be dropped to release the concrete arch. The hangars were destroyed by aerial bombardment in 1944.