Crane and surrounding area with historic buildings, river dam, restaurants and bars is the most iconic, relaxing and beautiful part of the town. Almost I could feel being few hundred years in past. Be prepared to take dozens of pictures all over the place.
The Alter Crane is an historic site on the river. You'll probably pass it walking to or from the station. I'm not sure if you can visit the interior - I was passing about 7pm. In the evening sun you can get some good photographs in the area.
It's an intereting site but not a must-see.
Part of the city guided tour; the “Alter Kran” was the most important visit in my opinion. I saw it inside out and study a little bit the mechanism and functional details. I was amazed to find out that the crane was powered by several people running inside like hamsters…