The Baden Black Forest Railway (German: Badische Schwarzwaldbahn) is a twin-track, electrified railway line in Baden-Württemberg, Germany, running in a NW-SE direction to link Offenburg on the Rhine Valley Railway ("Rheintalbahn") with Singen on the High Rhine Railway ("Hochrheinbahn"). Passing directly across the Black Forest, through spectacular scenery, the route is 150 km long, ascends 650 metres from lowest to highest elevation, and passes through 39 tunnels and over 2 viaducts. It is still the only true mountain railway in Germany to be built with two tracks, and is the most important railway line in the Black Forest. It was built between 1863 and 1873, utilizing plans drawn up by Robert Gerwig.