Hangar Y in the Forêt de Meudon near Paris was constructed between 1879 and 1884 for the dirigible La France by Charles Renard (1847-1905) and Arthur Constantin Krebs (1850-1935), and is reckoned the first of its kind in the world. Its metal doors were designed by Henri de Dion (1828-78) for the Paris Universal Exhibition of 1878. The hangar is 70m long, 24 m wide and 20m high. It formed part of a military air base in Charlais Park, served as a workshop for making balloons in the First World War, and for many years was an outpost of the air museum at le Bourget airport. It is designated as an historical monument, and was inscribed on the French tentative list for designation as a UNESCO World Heritage Site in 2002. After falling into disrepair it is now well-maintained and open to the public from time to time. The restoration work has been carried out under the auspices of the Centre Européen des Ballons et Dirigeables de Challais-Medon, together with the municipality of Meudon and the Aeroclub de France whose patron is the astronaut Audouin Dollfus.