Schloss Mellenthin, Renaissance manor house in Mellenthin, Germany.

Schloss Mellenthin is a three-winged manor house built between 1575 and 1580 on an artificial island about 100 m long and 80 m wide, encircled by a roughly 20 m wide moat with retaining walls. The main building is a two-storey, seven-axis rendered brick structure with a hipped-gable roof, a broad single-axis central risalit and two narrower side risalits on the courtyard side. An open entrance porch with a round arch and groin vault, added in 1904, carries a 1596 memorial plaque and the Neuenkirchen family coat of arms.

The castle was built between 1575 and 1580 for Rüdiger von Nienkerken, an advisor to Duke Ernst Ludwig. Ownership later passed through Swedish and Prussian noble families across the centuries.

The name Mellenthin has been documented since the 14th century as a seat of the von Neuenkirchen family. A plaque and family coat of arms from 1596, placed by Christoph von Neuenkirchen in memory of his father, the builder, are set into the entrance porch. Since October 2011 a Gasthausbrauerei has operated in the right wing, and a shop with a coffee roastery occupies the former castle chapel.

The manor house is reached by an avenue lined with the former estate farm buildings. The left side wing, once the stables, now holds the hotel; the right wing houses a glass extension built for the 2011 brewery, with its production rooms and a guest terrace. The former chapel contains a shop with a coffee roastery.

The moat around the artificial island is about 20 metres wide, and its banks are held by retaining walls. The island itself measures roughly 100 by 80 metres. The two side wings touch the main house only at their corners and have no internal connection to it.