Schloss Schönstadt, Medieval castle in Schönstadt, Germany.

Schloss Schönstadt is a two-story, seven-bay manor house with a mansard roof, built 1749–1751 for Georg Friedrich Milchling von Schönstadt on the site of a 13th-century water castle first documented in 1344. The only surviving part of the castle is its octagonal late Gothic tower stump, heightened by two half-timbered stories in 1618. A second tower was added around 1900.

The castle was first documented in 1344 as a water fortress with defensive moats surrounding its walls. Major renovations took place between 1749 and 1751 under the direction of Georg Friedrich Milchling von Schönstadt.

The castle passed through generations of noble families, from the Milchling dynasty to the von Bethmann family through marriage connections.

Schloss Schönstadt and its estate are entirely private property and not open to the public, so the interior cannot be visited. The grounds are likewise closed; the buildings can only be seen from outside, from the public roads and paths of Schönstadt at the southern edge of Cölbe.

The chemist and entrepreneur Eugen Lucius, co-founder of Hoechst AG, bought the estate in 1890 from Ludwig Ferdinand Milchling von Schönstadt. He had the castle renewed around 1900, adding a second tower. The property passed by inheritance to his daughter Eugenie, married in 1887 to the Dutch count Lodewijk Hieronymus Schimmelpenninck.