I always make a point to go to the Rathaus and ride them when I visit.
The floors fold up where the lift's floor meets the building's floor to prevent crushing your foot. It also has a switch which immediately stops the paternoster and sounds an alarm. I had not realized that and stopped the system while showing it to my son.
There is a list in the German Wikipedia[0].
[0]: https://de.wikipedia.org/wiki/Liste_von_Paternosteraufzügen
My mother’s workplace had one when I was about seven, and I was terrified even to think about it.
I had a go on this a long time ago, the building was empty on Saturday and they turned the elevator on just for us who were having a programming competition there. We rode in circles, went over the top and jokingly returned in handstands, jumped on and off on each floor... And while they are generally pretty safe - each platform in upward shaft and in the cabin was on hinges, each top of the "door"frame and top of the cabin had a hanging piece of wood and if any of these things were moved, the elevator would stop, so your feet or other body parts won't be crushed if stuck between the cabin and the frame. But still, you can hurt yourself pretty badly (think broken bones or head injury) just from slipping or falling forward/backward if you try to step on or off too soon or too late.
Being twenty-somethings, we had a great fun on them, but if you think of people you see daily moving on escalators, in the mall, on the pavement, you can pretty easily see that an older person or a less coordinated person may have a problem with them.
Btw. For the brave out there, there is also an industrial "version" called belt manlift. Dying on them is pretty easy.