There are hundreds of meters of these rails in the old Guido coal mine in Zabrze (south of Poland). They are located on 3 levels, the deepest being 355 meters below the ground.
It was the stone coal that was transported in these carragies for around 70 years (1855 – 1925). Now the mine is turned into museum that you can visit only with a yellow helmet on your head:)
My contribution to Cees Fun Foto Chanllenge – Tracks.