Cologne Cable Car (Kolner Seilbahn)

It is located in the northern part of the city, easily accessible by subway (metro Zoo / Flora line 18). It is only open for part of the year, from March 15 to November 10, from 10 am to 18 pm. Prices are € 4.50 one way and 6.50 for a round trip with several discounts for groups of 4 people. You can check all the information on their website 'https://www.koelner-seilbahn.de/german/index.html.' Maybe it isn't a "must do" but it can be a nice excursion, the view over the Rhine and the city are amazing.