I am going to be at a conference in Hamburg near the end of July. While most of my time will need to be spent at the conference (a pity), I have 1.5 days in the middle free for sightseeing. Can anyone suggest an interesting trip? I would especially be interested in seeing something related to German history (pretty much anything medieval through 20th century).
I won't have a car for the conference, but could rent one for a couple days, if necessary. Otherwise, I'll be relying on public transport.