Schloss Karlsburg, Baroque manor house in Karlsburg, Germany.

Schloss Karlsburg is a Baroque manor house in Karlsburg, featuring a three-story brick structure with a central building and symmetrical side wings. The mansard roof and classical architectural elements throughout give the building its distinctive shape and style.

Construction began in 1731 and the mansion served as a residence for the von Bismarck-Bohlen family until 1945. After World War II, the building was repurposed first as a specialized clinic and later transformed into a research facility.

The name honours the owner, Count Carl Julius von Bohlen, not the guest: after Gustav III of Sweden spent a night here in 1771, Gnatzkow became Carlsburg, now Karlsburg. The park behind the house was laid out in French style from 1750, with a pond, an island and a marble statue of Flora, and was redesigned as an English landscape park around 1800 to plans by Peter Joseph Lenné.

The mansion is now owned by the state of Mecklenburg-Western Pomerania and houses research institutes of the University of Greifswald. Since it is used for academic purposes, visits should be arranged in advance.

The last owner, Count Fritz Ulrich von Bismarck-Bohlen, housed the University of Greifswald's collections in the castle from 1942, including the Croÿ tapestry of 1554–1556, and opened a children's tuberculosis ward in the west wing in 1943. He took his own life on 28 April 1945 as Soviet troops arrived.