Burgruine, Medieval castle ruins in Partenstein, Germany.

Burgruine is a medieval fortress situated on a 240-meter (787 ft) hill at the junction where the Lohr and Aubach rivers meet in Bavaria. The stone remains show walls, defensive structures, and entrance areas that once formed a complete castle complex.

The Counts of Rieneck founded the castle shortly before Partenstein's first documentary mention in 1233, overseeing the trade route from Lohr to the Wiesbütt crossroads. In 1333 it passed to the Lords of Hanau, and in 1339 it was divided between Hanau and Mainz. By the 16th century the Mainz bailiff lived outside the castle because it was no longer habitable. In 1633, during the Thirty Years' War, it was conquered and destroyed, then used as a quarry.

The ruins reveal medieval construction methods and defensive designs that are now visible through careful excavation work. This site has become central to how locals understand their town's past and connection to the surrounding landscape.

The ruin sits on a spur of the Schlossberg at 240.5 m above sea level, just southwest of Partenstein above the confluence of the Lohr and Aubach. An information board on site explains the results of the archaeological excavations that have been running since 2003. Parts of the Zwinger, the castle wall and the entrance have been excavated and are partly restored.

The name comes from medieval German words where 'Barte' means axe and 'Stein' means stone. The town of Partenstein honors this origin in its coat of arms, which displays two halberds as a direct reference to the castle's ancient name.