Chemins de fer Orientaux
The Chemins de fer Orientaux (English: Oriental Railway; Turkish: Rumeli Demiryolu or İstanbul-Viyana Demiryolu) (reporting mark: CO) was an Ottoman railway company operating in Rumelia (the European part of the Ottoman Empire, corresponding to the Balkan peninsula) and later European Turkey, from 1870 to 1937. The CO was one of the five pioneer railways in the Ottoman Empire and built the main trunk line in the Balkans.