Mainau  is an island in Lake Constance (on the south shore of the Überlinger See near the city of Konstanz, Baden-Württemberg, Germany). It is maintained as a garden island and a model of excellent environmental practices. Administratively, the island has been a part of Konstanz since December 1, 1971, when the municipality of Litzelstetten, of which Mainau was part, was incorporated into Konstanz.