I suggest the metro line U3 from the german harbour city Hamburg. The U3 is a cirle line from Barmbek to Barmbek with a short branch to Wandbek-Gartenstadt and is mostly over the ground but in the citycenter it’s also under the ground. The route also included the famous elevated and famous part at the hamburg harbour from Landungsbruecken to Roedingsmarkt, next to some of hamburgs most famous sights like the Elbphilharmonie, the St. Michaelis church and the Landungsbruecken. Almost every service on this route is driven by the DT5 metro train especially developed for this route with its particularities. Here the Map of the Route: Here some Photos from the Route with a „DT5“: Here one Picture with the older „DT3“ at the underground station „Rathaus“ (Town Hall):
Awesome suggestion, would love to see Hamburg S bahn! Then for Hamburg - Lübeck there will be AI services then and for that route AI services from HBL! And finally some german 3rd rail