Herrenhaus Blankensee, Manor house in Trebbin, Germany.

Herrenhaus Blankensee is a two-storey baroque manor with a rectangular footprint of 15 by 30 metres, nine axes and a mansard roof, built on a high rendered base. Its front is dominated by a colossal-order central riser with a triangular gable, and the facade has pilasters at the corners. It stands in Blankensee, part of Trebbin in Brandenburg, east of the Nieplitz.

An earlier castle once stood on this site but was destroyed by fires in 1615 and 1655. Christian Wilhelm von Thümen rebuilt the location with the current baroque manor between 1739 and 1741, which later became home to the writer Sudermann.

Hermann Sudermann leased the estate in 1897 and bought it in 1902, commissioning Berlin architect Otto Stahn to remodel it. Sudermann laid out the park with statues from his travels, marble benches, small bridges over the Nieplitz and an Italian garden. After his death in 1928 his heirs set up the Sudermann Foundation, which was to offer refuge to writers in need.

The estate can be visited through guided tours that specifically focus on the Sudermann memorial rooms and the historical chambers. Advance arrangements are recommended for visitor access, and the tours provide insight into how the manor was used during its literary period.

The Sudermann memorial room was specifically arranged to document his life and artistic work at this location, displaying personal objects and documents that reveal his connection to both the manor and its surroundings. This dedicated space offers a window into how a literary figure of his era worked and lived.