It was back in 2006, on my way to visit a girlfriend in Poland, that I first spent two fun weeks exploring the North of Germany (Lubeck, Hamburg & Berlin). Three very contrasting locations, each most definitely worth spending more time in than I had available (and maybe with more money too, next time!).
Lubeck is quaint, with a lovely old town, Hamburg is pure industry, with HUGE canals, and Berlin is massive and metropolitan, with so so much history thrown in! You can read more about my experiences in each city below.
I've since been back once or twice, but there is so much of this wonderful country that I have yet to see, that I'm sure I'll be returning again soon!