Lyon Metro line C

Line C of the Lyon Metro is quite interesting. The section between Croix Paquet and Croix Rousse was opened in 1891 as a funicular railway, i.e. trains were hauled up and down by cable. In the 1970s, it was renovated and converted to a rack railway, i.e. a cog wheel underneath the train engages with a rack between the rails to help it up the steep slope. When the first two regular metro lines opened in 1978, it became line C and was extended (with rack) to Hotel de Ville. Leaving Hotel de Ville, there is a noticeable downward slope before it heads uphill. Finally in 1984 the northern end, up the hill, was extended (without rack) to Cuire.

The lower station of the original section, Croix Paquet, is claimed to be the steepest Metro station in the world (which I can believe) with an incline of 17%. Also, it's opening in 1891 makes it some of the oldest Metro infrastructure in the world, predating Budapest and Paris.