Ahlden House is a stately home at Ahlden on the Lüneburg Heath in Lower Saxony, Germany. It was built in 1549, originally as a water castle on the river Aller, which has since changed its course. Nowadays the three-winged mansion is a private residence and is used as an arts auction house.
It is principally known as the place of imprisonment of Sophia Dorothea of Celle, otherwise Sophie Dorothea of Brunswick-Lüneburg, wife of George I of Great Britain and the mother of George II of Great Britain.
Wikipedia https://en.wikipedia.org/wiki/Ahlden_House
Coordinates 52°45'33.175" N 9°33'28.652" E