The very nib of the Altstadt peninsula, the point where the rivers merge, is known as the Dreiflusseck. From the north the little Ilz sluices brackish water down from the peat-rich Bavarian Forest, meeting the cloudy brown of the Danube as it flows from the west and the pale snow-melt jade of the Inn from the south to create a murky tricolour. The effect is best observed from the ramparts of the Veste Oberhaus.