The Castle can be visited
Museum
Celle Castle

Celle Castle, a four-winged complex, is in the southern Lüneburg Heath and was once a residence of the House of Brunswick-Lüneburg. Originally built as a fortified defensive tower guarding a ford across the Aller river, it evolved into one of the region's largest castles.
History+
The castle's origins trace back to around 980, when a Brunonian count erected an initial fortification named 'Kellu'. Around 1292, Otto the Strict founded another precursor castle, whose cellar vaults and parts of the watchtower can still be found today beneath the castle theater. The first documented mention as 'Castrum Celle' occurred around 1315. Following the Lüneburg War of Succession, the Dukes of Brunswick-Lüneburg moved their residence to Celle from 1378 and began transforming the fortified complex into a castle. Between 1471 and 1478, Frederick the Pious significantly expanded the complex, and the castle chapel was consecrated in 1485. Ernst I had the castle decorated in the Renaissance style from 1530 and relocated the fortifications.
Source: Wikipedia · Licence: CC BY-SA 4.0 · Image: Joachim Schneeleopard
This description draws on the facts documented in the linked Wikipedia article; Wikipedia content is licensed under CC BY-SA 4.0. Wording and editing: Mobile History.
Location: 52.6239, 10.0775