The Hinterhaus ruin, also known as the Oberhaus, is an almost thousand-year-old weir system in Spitz an der Donau, Lower Austria, on a foothill of the Jauerling. It was first mentioned in 1243. The ruins in the area of ​​the Wachau are located near the "Thousand Bucket Hill", a vineyard that produces a certain amount of grapes every year, and on a rocky ridge of the so-called Hausberg, part of the Jauerlingstock. The " Riesling " grape variety has its origins nearby.

The hilltop castle is clearly divided into three separate parts: the lower northeastern outer castle, the main castle, which takes up most of the rock ridge, and the southwestern outer castle.

The oldest part - the main castle - already existed in the 12th century. In the 13th and 14th centuries, the knights of Spitz ruled this castle, who in turn was subject to the Kuenringern.

In an Austrian excursion tip, it says: “There are many legends and stories about the ruins of the rear building. It is said that this ruin is still haunted today. The ghost of the late Adelheid, wife Heinrich the Iron, appears every year on the anniversary of her husband's death in the ruins of the rear building in the Wachau. Heinrich married a new woman shortly after her death, although at that time there was a year of mourning. Shortly afterward he died too. Many saw it as a punishment for his shameful behavior. "