Burg Sulzberg, Medieval castle ruins in Sulzberg, Germany

Burg Sulzberg is a castle ruin on a hill above the village of Sulzberg in Bavaria, Germany. It consists of a Romanesque residential tower and a defensive keep called the Bergfried, with sections of the original stone walls still standing around them.

The Sulzberg family is first documented in 1176, and construction of the castle is assumed around 1170. The male line died out in 1359, after which the castle passed to the related Schellenberg family by 1525. From 1480 to 1485 Marquard von Schellenberg expanded it and renamed it "Schloss Sigmundsruh" after Archduke Sigismund of Austria. In 1525 it was sold to the Prince-Abbot of Kempten.

The castle's name changed in 1480–1485, when Marquard von Schellenberg rebuilt it and called it "Schloss Sigmundsruh" after his lord, Archduke Sigismund of Austria. The small castle museum in the 24 m Bergfried displays original finds from the 1991/92 excavations; it opens on Sundays and public holidays in the afternoon, when the viewing platform is also accessible.

The ruin is best reached on foot from the center of Sulzberg village, following the path that climbs the hill. The trail can be slippery in wet weather, so sturdy footwear makes the visit more comfortable.

The Bergfried was not meant as a living space but as a last refuge during an attack, with its entrance set high above ground level to slow down any intruder. Climbing it today gives a clear sense of why this hilltop position was chosen to watch over the surrounding land.