Rittergut Patthorst, Manor house in Steinhagen, Germany.

Rittergut Patthorst is a late Baroque manor house built in 1773 by the von Closter family on a moated island in Steinhagen. The main building has eight axes, a flat hipped roof and a central risalit crowned by a triangular pediment, with a free staircase leading to the entrance. West of the house stands the 1818 mausoleum of cathedral canon Carl Heinrich von Closter.

Patthorst began as a hunting lodge of the Counts of Ravensberg and became the seat of the von Closter family at the end of the 14th century. Wilhelm von Closter received it as a fief in 1463 and was marshal to Duke Adolph of Jülich and Berg in 1486. The line died out with Caspar Heinrich (d. 1813) and his brother Franz Wilhelm, a royal captain at the storming of the Zahlbach redoubt before Mainz in 1794; heiress Therese von Closter married Karl Christian Heinrich von Eberstein, owner from 1830. The estate became a Gutsbezirk in 1859 and was incorporated into Brockhagen on 1 October 1928.

The name Patthorst comes from the von Closter family, who held the estate as a fief from 1463 and died out in the male line in 1813. Their heiress Therese von Closter married Karl Christian Heinrich von Eberstein in 1803, and the Freiherren family Eller-Eberstein has lived at the house ever since, running it as a forestry operation and horse farm.

The manor house on its moated island and the surrounding landscape park belong to a private estate run as a forestry operation and horse farm by the Eller-Eberstein family. There is no public visitor programme, so access to the grounds is only possible by prior arrangement with the owners.

The 1818 mausoleum west of the main house holds the tomb of cathedral canon Carl Heinrich von Closter; the Great Cross of Baron Ernst von Eberstein stands there too. The late-Baroque house of 1773 likely reuses masonry from a medieval castle on the same island.