March 1913:
Ferdinand Mülhens, owner of “4711 – Eau de Cologne”, purchases the railway business from the Deutsche Lokal- und Straßenbahngesellschaft.
April 1924:
By authority of the Reichsbahndirektion (State Railway management), the Petersberg and the Drachenfels cog railways are amalgamated under the name “Bergbahnen im Siebengebirge” (Mountain Railways in the Seven Hills).
September 1939:
The beginning of World War II has great impact on the operation of the railways. But despite major restrictions during the years of the war, the service is never discontinued. After the war, homecoming prisoners of war and local helpers restore the mountain railways to their original state.
March 1955:
After a period of 72 years, electrically driven locomotives gradually replace the steam engines. On the Drachenfels, however, the latter remain in service until 1960.
July 1957:
The valley station is extensively rebuilt and renovated. Concrete, steel and quarry stone walls give it its characteristic features, which it has retained until today.
A new type of roof design, open to the sides, protects the visitors from wind and weather.
November 1999:
The modernisation of the electrically driven locomotives begins. The work is completed in 2001.