Ahlden House, Renaissance château in Ahlden, Germany.

Ahlden House is a three-winged mansion complex on the Aller river with a Renaissance facade and two stories. The structure is surrounded by former moats and ramparts that mark its earlier defensive purposes.

Built from 1549 as a water castle on the Aller, the south wing was completed in 1579 under Duke William the Younger, and the west wing in 1613 under Duke Christian the Elder. From 1694 Sophia Dorothea of Celle, wife of George I, was held here for 32 years until her death in 1726. The Amt Ahlden was dissolved in 1884, and from 1852 to 1972 the building served as the district court.

The house is known as the "Princess of Ahlden" site: Sophia Dorothea of Brunswick-Lüneburg, wife of George I of Great Britain, was held here from 1694 until her death in 1726. Her fate entered literature, and the name Ahlden became attached to her. Since 1975 an arts auction house has used the building, and the courtyard stays open to the public during the day.

The interior spaces are open to visitors during art auctions, while the courtyard is regularly accessible. It is wise to check current opening times beforehand and visit the website for updates.

The Bunkenburg stood on the opposite bank of the Aller, not on the site of the present house. In 1618 a flood shifted the Aller eastward, and embankments upstream sent Leine water through the old bed, which has been called the "Old Leine" since. The moats were filled in during the 19th century; a remnant of the rampart survives in the north.