danube river and werenwag castle in autumn, swabian alb, baden-wuerttemberg, germany

danube valley river castle swabian alb autumn germany baden wuerttemberg rock rocky hilly upper nature reserve water leaf colors fall scenic mountain hill waterfront riverbank scenery autumnal park german landscape foliage tree coloration broadleaf deciduous donautal sigmaringen district picturesque idyllic tranquil southern travel tourism destination outdoors baden-wuerttemberg