Burg Reinsberg, Medieval castle in Reinsberg, Austria.

Burg Reinsberg is the ruin of a hilltop castle above the village of Reinsberg in Lower Austria's Scheibbs district. Its oldest part is the Palas at the upper courtyard, now supplemented by steel-reinforced concrete supports and balcony-like steel structures. The lower courtyard holds a mobile elliptical roof carried by a stationary used truck crane and anchored with steel cables.

Burg Reinsberg was first documented in 1215, when Bishop Otto II of Freising claimed a castrum in Rainsperch held as a fief of the bishops of Regensburg. In 1256 Engelschalk von Reinsperg held it; after his death his widow Adelheid was enfeoffed with Reinsberg and Wang. The Auersperg family owned castle and lordship until 1834, when Emperor Franz I acquired the ruin; since 1997 it has belonged to the municipality of Reinsberg.

The grounds now host the Burgarena, an open-air venue where theatrical and musical performances take place. This transforms the castle into an active gathering space for entertainment during the warmer months.

The site is best reached on foot and offers good views from its elevated position over the surrounding area. Visitors should expect uneven ground and stairs, as this is a partially restored ruin that requires careful walking.

The lower courtyard features a mobile roof system protecting around 900 seats, allowing performances to continue regardless of weather. This practical solution merges historical setting with modern operational needs.