The Amper is a river in southern Bavaria, Germany and is the biggest (left) tributary to the Isar river. It meets the Isar river in Moosburg after a length of 185 km. It runs out of the Ammersee and its upper course, upstream from the Ammersee, is called Ammer. Cities along the Amper are Fürstenfeldbruck, Dachau and Moosburg. Its biggest tributaries are the rivers Glonn, Würm and Maisach.