We are flying into Frankfurt July 2. We have to go to a wedding in Berlin on July 6. What should we do until then? We were thinking a couple days in Frankfurt area and a couple days in Cologne or Hamburg. We won't have a car, so ideally we would like to be based in destinations served by EC/IC/ICE trains.
Any thoughts on how long in Frankfurt/Cologne/Hamburg or suggestions for other destinations? We like to eat, drink beer, drink wine, museums, castles, history, and day hikes/bike rides/boat rides.