Burg Schlüsselburg, Castle in Schlüsselburg, Petershagen, Germany

Burg Schlüsselburg is the surviving south wing of a two-winged complex built between 1581 and 1585, replacing the original 1335 structures; the north wing was demolished in the 19th century. The building stands west of the Weser in the Schlüsselburg district of Petershagen. A stork's nest has occupied the chimney of the north gable continuously since at least 1935.

Bishop Ludwig von Minden built the castle in 1335 as an outpost of Petershagen, guarding against attacks from the north, especially by the Counts of Hoya at Stolzenau. It became one of five administrative castles of the Prince-Bishopric of Minden. Financial troubles led to its pledge to the von Münchhausen and von Klencke families, and its military role declined in the 15th century. After the Thirty Years' War it served as the office building of the Amt Schlüsselburg; in 1846 the town acquired it, using it for administration until 1934 and as a school until 1961.

The castle's name comes from the key in the coat of arms of the Bishopric of Minden. From 1846 it belonged to the town of Schlüsselburg, housing the Amt administration until 1934 and a school until 1961. Since 1971 the Swoboda family has restored it; it remains private and closed to visitors.

The castle is privately owned and not open to the public, so it can only be seen from outside; do not enter the grounds. It stands just west of the Weser in the Schlüsselburg district of Petershagen. The surviving building is the remnant of a two-wing complex, its north wing demolished in the 19th century.

The north wing was demolished in the 19th century, leaving only one wing of the 1581–1585 building. On the chimney of the north gable a stork's nest has been continuously occupied at least since 1935, a detail visible from outside.