Blautopf spring – Blaubeuren,Germany is a spring that serves as the source of the river Blau in the karst landscape on the Swabian Alb’s southern edge, in Southern…

Blautopf spring – Blaubeuren,Germany is a spring that serves as the source of the river Blau in the karst landscape on the Swabian Alb’s southern edge, in Southern…