The Stuttgart–Horb railway is a 67.227 kilometer-long railway in the southern part of the state of Baden-Württemberg in Germany, running from Stuttgart to Horb. It forms part of a railway known as the Gäubahn () or Gäu Railway. The Royal Württemberg State Railways (Königlich Württembergischen Staats-Eisenbahnen or K.W.St.E.) and the Baden State Railways (Badische Staatseisenbahnen) constructed the majority of this line between the years 1866 and 1879. Today the partially single-track, fully electrified line features the high-speed Intercity-Express (ICE) service, with its tilting train technology, traveling from Stuttgart to Zurich. In addition, a multitude of local train services of numerous railway companies are on offer. The Gäu Railway is also a significant line in the North-South freight service system. Route details The Gäubahn steadily ascends from Stuttgart Hbf in a continuous loop around the city center, which, due to its superb views of the basin of the Stuttgart valley, lent the name "Panoramabahn" to this section, and counts as one of the most beautiful city center railways in Germany. From the city it heads in a southwesterly direction, and runs alongside the nature park Schönbuch between Böblingen und Herrenberg. From there, the line runs through the eponymous Gäu to Eutingen. The route then descends into the Neckar valley and brushes up against some of the easternmost parts of the Black Forest, until it leaves the Neckar valley near Rottweil, and follows the Prim valley. Between Rottweil and Tuttlingen, the Gäubahn then traverses the Baar region at the foot of the Heuberg. Near Balgheim, the line then exits the Prim valley, and follows the Faulenbach and Elta to Tuttlingen, where it crosses the Danube. Until its end, the Gäubahn now takes a southerly direction. Near Hattingen, the line meets up with the Black Forest Railway (Schwarzwaldbahn), crosses the volcanic landscape of the Hegau, travels parallel to the Aach river for part of the way, and passes by the Hohentwiel shortly before its terminus in Singen. Near Spaichingen and Hattingen, the line crosses the main European watershed between the Rhine and Danube rivers. The Gäu Railway is a main line railway, 148.5 kilometers in length. The entire route is electrified and is constructed to be used by the ICE tilting train technology. The line features twin tracks between Stuttgart and Horb and has a total of four tracks between the stations Stuttgart-Österfeld and Stuttgart-Rohr, a 3.5-kilometer-long section. The Gäu Railway and Nagold