Jena partly lies in the middle hall valley between from mixed woodlands covered shelly limestone and sandstone slopes (geological phenomena are among other things the devil holes and the student chute). On them numerous partially rare Orchideenarten occurs. From north to south Jena is 14.7 km (9.1 mi) wide, and from east to west 12.2 km (7.6 mi). The following larger cities are close to Jena: Gera, approx. 35 km (21.7 mi) east, Erfurt, approx. 40 km (24.9 mi) west, Weimar, approx. 15 km (9.3 mi) west, Naumburg (Saale), approx. 33 km (20.5 mi) northeast, is (Saale), to approx. 70 km (43.5 mi) northeast, Leipzig, approx. 75 km (46.6 mi) northeast and Chemnitz, approx. 94 km (58.4 mi) east, Rudolstadt, approx. 30 km (18.6 mi) south.