Enjoy a scenic rhine river cruise from cologne to the resort city of knigswinter at the foot of the beautiful siebengebirge hills after a journey down the water that takes in sights of romantic riverside villages and hilltop castles choose to visit one of two knigswinter attractions either visit the family friendly sea life aquarium or ride one of germanys oldest cogwheel railways up to the famous drachenfels cliff topped by fascinating ancient ruins of drachenfels castle