The Wuppertaler Schwebebahn (English: Wuppertal Suspension Railway) is a suspension railway in Wuppertal, Germany. The line was originally called the German: Einschienige Hängebahn System Eugen Langen (English: Eugen Langen Monorail Overhead Conveyor System) named for its inventor, Eugen Langen. It is the oldest electric elevated railway with hanging cars in the world and is a unique system in Germany.
https://www.cnn.com/travel/article/wuppertal-schwebebahn-suspension-railway-germany/index.html
It’s also just cool and fun. I imagine a decent number of us train nerds end up visiting Wuppertal because we heard about the upside down train.