In 1961, a group of young designers practising under the name of Atelier 5 completed Siedlung Halen near Berne. This private housing development was the first built example of the compact, low-rise housing type conceived by Le Corbusier for vacation use in the south of France. It was the forerunner of the newly resurgent carpet or mat planning form. In addition, Halen was a social experiment likened by its designers to the Unité d'Habitation at Marseilles, reinterpreted to fit closely with the local topography. Beyond its undisputed claim to history, its success resides, as in the case of the Unité, in having raised the standards of a particular housing form. Attention to the welfare of users has since become a hallmark of the work of Atelier 5. This paper describes the genesis of the project, its form and social outlook.