What to see between Copenhagen and Dusseldorf?

Berlin or Amsterdam could work.

Hamburg is half way. Lueneburg just a short train ride away and still on the way to Duesseldorf.
Edit - Luebeck is also on the way.

Berlin and Amsterdam are seriously out of your way. As Sam suggested try Hamburg or Lueneberg. Or Bremen might be worth it. Try looking at all those cities and see what looks interesting.

Hamburg makes a great stop. I took the bus/ferry combo from CPH to Hamburg to visit a friend, then we went on to Berlin; I made the trip in reverse.

Thanks! I decided on Lubeck and Luneburg. Both have interesting history and historic town centers. Just the type of place I like.

Hamburg, Bremen, Lübeck, Lüneburg, all great places.

Here's a completely different idea for you: How about a stop on an island? Have a look at Westerland/Sylt. (You can actually get there by train.)

Hi,

Depending on how far you want to deviate, I would say Lüneburg (as suggested, plus one of my top favourite places in Germany), Minden an der Weser, Lübeck, Münster/Westf., Soest, Eutin/Holstein. Numerous places in the North Germany, depends on your priorities. As regards to cultural and war history, etc. there are plenty of places (Wesel, Minden, Ratingen, Essen, Duisburg, Lüneburg, Münster, Eutin, Düsseldorf, Kiel, etc) from Düsseldorf to Copenhagen where a particular museum or memorial is located in that town.

@ Brenda....You made the right choice on picking Lüneburg, a lovely, relaxing town...one of my favourite towns in Germany. See the Johanniskirche, just before the Stadtmitte. . It was one town not devastated by the war, quickly occupied by the British when they got to the low Elbe area, and was the site for Tac HQ for the British Army in 1945...not the town itself though.