The Paris métro comprises 14 lines, some 300 stations and 201.8 kilometres of track. At any one time there are around 540 trains travelling on the system, and at busy times even more, carrying around 5 million passengers every day.

But in 1903, three years after the Grand Opening of the metro, engineers didn't figure out all the kinks yet, leading to the biggest fire in the Paris métro, the fire of the Couronnes station...