For over 20 years, a Catholic youth organisation has been using this former electricity substation at an old railway station as a mountain hostel and educational centre. It is located in the village of San Lugano in South Tyrol in northern Italy. The architects were asked to make the building suitable for winter use, and to provide extra sleeping accommodation. The local zoning plan prevented the construction of any permanent new buildings, because the old railway route is later to be developed as a bypass. Mobile structures, however, were allowed. The architects’ response was to design five “sleeping cars” resembling real railway wagons in appearance and dimensions. This also fitted in well with the former function of the site, and stood as a metaphor for mobility. Four of the cars are fitted out with two platforms to sleep 10 people, a washroom and a cupboard area; the fifth serves as a storeroom. These temporary structures rest on old railcar mountings that were due to be scrapped; they stand on 50 metres of newly-laid track. Steel ladders between the cars lead up to a covered entrance area.The walls, roofs and floors of the cars are made up of highly insulated prefabricated wooden panels brought to the site by truck and mounted on the base within a week. The façades are clad with grey-painted softwood boards, and all interior walls, ceilings and floors are lined with natural-coloured OSB, the surfaces of which are simply sanded and oiled. Inside, the beds, cupboards and robust wooden units are arranged and fitted like in a real railway carriage: everything is compact, simple and functional. Colour is used only on the window reveals which stand out in the twelve different colours.