Schloss Reitenau, Medieval castle in Grafendorf bei Hartberg, Austria.

Schloss Reitenau is a fortified castle with a courtyard surrounded by arcades, a chapel, and defensive walls in Grafendorf bei Hartberg. The structures create an enclosed residence that sits above the surrounding landscape on elevated ground.

The castle developed in the 14th century as a water castle built on the site of an earlier estate from 1160. Ownership shifted over time as different families took control of the structure and its surrounding lands.

The name Reitenau derives from the Reuter family, who held the estate from the Counts of Stubenberg and rebuilt the farmstead as a small water castle at the start of the 14th century. The castle is first recorded in 1340 as Burg zu Grafendorf, and the Reuter name stayed attached to the site after the family died out in the male line in 1427.

The castle has belonged to the Lentz family since 1939 and is privately used, so it is not freely accessible. The site lies in the Stambach area of Grafendorf bei Hartberg, about 5.5 km north of Hartberg and 424 m above sea level. Any request to view the property should be addressed directly to the owners.

Over centuries, the estate was repeatedly divided among heirs, leaving only the gate and moat as shared property by 1563. These divisions reveal how family inheritance affected the physical structure and use of the castle.