Goslar

Goslar needs 1 day: the Kaiserpfalz (an 11th-century imperial palace, one of the largest medieval secular buildings in Europe) and the old town, with over 1,500 half-timbered houses, on the same walk. May-September is best, though Goslar is also a winter base for the nearby Harz mountains. It's cheaper than similar destinations like Rothenburg. It was for centuries the seat of Holy Roman Emperors and a mining power thanks to the nearby Rammelsberg mine -worked continuously for over 1,000 years-, both UNESCO World Heritage Sites.