The German city with an incredible upside down railway
https://edition.cnn.com/travel/article/wuppertal-schwebebahn-suspension-railway-germany/index.html
This type of railway must have been convenient, when roads were not enough paved and there are no enough roads to ease traffic jam in mountainous cities. But now, roads in most of the cities in developed countries are fully paved. So, it's no longer superior to road traffic, except for environmental aspect. It would be important to reduce initial cost ,and to reduce operation cost in order to make it compatible against road traffic.
