Wroclaw

Wrocław is built across islands and bridges, and the old town is small enough to walk: the market square, the university, the cathedral and the Centennial Hall, with the dwarfs hidden on nearly every street.

Its history is the other half of the story — from Breslau through the war to the rebuilt city you see now. Three days covers the centre and one day trip, and the hotel I recommend is right by the main station.