The Château de l'Île is a former castle in Ostwald, France, which is now used as luxury hotel. The present building was built in 1891 by the entrepreneur Léonard Heydt (1829–1901), who also served as the mayor of Ostwald from 1861 until his death. It re-employs elements of a previous castle from the early 17th century, which had probably replaced an even earlier castle (the first mention of a castle in Ostwald dates from the year 1226).