You've probably seen the photo above before. The Montparnasse derailment occurred October 22, 1895 when the Granville–Paris Express overran the buffer stop at its Gare Montparnasse terminus. It entered the station too fast and the train air brake failed. After running through the buffer stop, the train crossed the station concourse and crashed through the station wall.
Here are 15 photos of other steam train accidents that are hard to explain.