Burg Scharfenberg, Medieval hilltop castle in Donzdorf, Germany.

Burg Scharfenberg is a ruined hilltop castle on a 617.1 m high summit above Donzdorf. Its 68 by 27 metre walled courtyard occupies the whole hilltop, protected on three sides by steep slopes and on the south by a deep ditch. Inside stand the ruin of a three-storey late Gothic building, a renovated residential tower now used as a holiday flat, and the ruin of the manor house with two oriels and a Renaissance portal.

The castle was founded in 1156 and belonged to the Scharfenberg family, who gained importance under Emperor Frederick I Barbarossa. Later renovations transformed it into a Renaissance residence, changing the medieval fortress.

The name Scharfenberg comes from the noble family von Scharphinberch, first mentioned in 1156 in a document issued by Emperor Frederick I Barbarossa for Maulbronn Abbey. The castle later served as the residence of the main Rechberg line until Donzdorf Castle was completed in 1568, after which a vogt and servants lived there. The entrance gate shows the Württemberg antlers on the left and a coat of arms with three crowns on the right.

Access to the ruins runs along a gravel path to the castle courtyard, though the residential tower remains privately owned and off limits. Wear sturdy shoes since the ground is rough and uneven in places.

The large blocks with a raised central boss on the eastern outer wall date from the 12th century, when the castle belonged to two free noblemen, Otto and Friedrich von Scharphinberch, named in a 1156 charter of Emperor Frederick I Barbarossa for Maulbronn Abbey.