Photo: GetYourGuideOne of the most popular things to do in Cologne, this hour-long panorama cruise glides along the Rhine past the cathedral, the old town, the Crane Houses and the Chocolate Museum, with the finest views of the skyline coming from the water. It is inexpensive and relaxing. Sit on the open deck if the weather allows, aim for a late-afternoon sailing for warm light, and have your camera ready for the Dom.