Celle is one of the best-preserved old towns in northern Germany, set on the River Aller at the southern edge of the Luneburg Heath. It has the ingredients that make a small German city worth a full day: a walkable Altstadt, hundreds of timber-framed houses, and a ducal palace that still feels like the town's centre of gravity.
The town was the residence of the dukes of Brunswick-Luneburg until 1705, and that courtly past still shows. Celle Palace mixes medieval castle, Renaissance residence, and Baroque theatre; nearby, St Mary's Church holds the ducal crypt and gives a good tower view over the old roofs.
Celle is not a museum town in the stale sense. The old streets still work as a town centre, with shops and cafes tucked into buildings that survived the Second World War largely intact. Add the Bomann Museum, the French Garden, and the picture-book carving of Hoppener Haus, and Celle makes a strong, easy day from Hannover or a good base for the Luneburg Heath.