The dividing line between Upper and Lower Harz follows approximately a line from Ilsenburg to Bad Lauterberg, which roughly separates the catchment areas for the Weser (Upper Harz) and Elbe (Lower Harz). Only on the southeastern perimeter of the Upper Harz, which is also called the High Harz (Hochharz) (Goslar, Göttingen and Harz districts), does the mountain range exceed NN on the Brocken massif. Its highest peak is the Brocken (1,141 m), its subsidiary peaks are the Heinrichshöhe (1,044 m) to the southeast and the Königsberg (1,023 m) to the southwest. Other prominent hills in the Harz are the Acker-Bruchberg ridge (927 m), the Achtermannshöhe (925 m) and the Wurmberg (971 m) near Braunlage. In the far east, the mountains merge into the East Harz foothills (Harz district, Saxony-Anhalt), which are dominated by the Selke Valley. Part of the south Harz lies in the Thuringian district of Nordhausen.