When the Merkur Was Blue... Merkur (in English, Mercury), the Roman god of trade, education and travel, was the namesake for one of the new long distance express trains introduced by the German Federal Railroad in 1952/1953. These blue long distance express trains linked the centers of the Federal Republic of Germany in the beginning of the Economic Miracle period. The F3 / F4 "Merkur" ran between Hamburg-Altona and Frankfurt am Main and/or Stuttgart. Coaches from the German State Railroad Group 35 were equipped with quality and distinction and were used as 1st class or 2nd class as demand dictated. The dining car from the same design group belongs to the period of the long distance trains fielded by the German Sleeping Car and Dining Car Company or DSG. Naturally, these flagship trains were pulled by the stars of the express train steam locomotives such as the class 05.