Ulm is the sixth-largest city of the southwestern German state of Baden-Württemberg, and with around 129,000 inhabitants, it is Germany's 60th-largest city. Ulm is located on the eastern edges of the Swabian Jura mountain range, on the upper course of the River Danube, at the confluence with the small Blau Stream, coming from the Blautopf in the west. The mouth of the Iller also falls within Ulm's city limits. The Danube forms the border with Bavaria, where Ulm's twin city Neu-Ulm lies.