Question: The Höllental (English translation: Hell's Valley) in the Black Forest is a deep valley - in places like a gorge - in the state of Baden-Württemberg in Germany, the valley, which is about 9 km long, is located in the southern part of the Southern Black Forest Nature Park about 18 km southeast of which city in Baden-Württemberg, Germany with a population of about 220,000?
Sentence (from "Black Forest Railway (Baden)"): 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.
Relevant evidence: No