Lindau (lĭnˈdou) [key], town (1994 pop. 24,560), Bavaria, S Germany, on an island in Lake Constance (Ger. Bodensee ). Connected by bridges with the mainland, it is a picturesque summer resort and tourist center and a base for lake steamer service to Austria and Switzerland. Lindau was an imperial city from 1275 to 1803 and passed to Bavaria in 1805.