The Elm is a range of hills north of the Harz mountains in the Helmstedt and Wolfenbüttel districts of Lower Saxony, Germany. It has a length of about 25 km (15.5 mi) and a width of 3–8 km (2–5 mi) and rises to an elevation of 323 meters. Surrounded by the Northern European Lowlands, the Elm is almost uninhabited and the largest beech forest in Northern Germany. The hills are of a triassic limestone called Elmkalkstein.