Duernstein Castle on a mountain near the city of Duernstein on the Danube- riverside in Nether Austria was in posession of the Kuenringer-knights in the 12th century. The Kuenringer were an old member of the Austrian aristicracy. But they had spend all their fortune for building their castle and for their servants. Therefore they became robber-knights. They fixed two strong sticks on both sides of the river Danube, fixed also a iron chain to the sticks. On the top of one stick a roll was positioned, where the chain was falling down to the earth. The chain, fixed to the sticks lies in the miidle of the river on the ground. Two horses were connected with the chain on it's roll-side. The horses draw the chain out of the river, driven by some knights, when the knight on the castle watched a rich merchant-ship aproaching down the river. The horses closed the river for the ship by drawing out the chain. The robber-knights covered this merchant-ship by arrows and then entered it by boats and robbed the ship out.
The new emperor of the Holy German Realm Rudolf of Habsburg heard about the criminal activities of the Kuenrings. He sent therefore a battle-ship, camoflushed as a merchant-ship, down the river Danube to Duernstein. Many caskets stood on the deck of this ship and behind these caskets were many canons positioned. The canons fired by all their power on the Kuenring-knights, who wanted also to rob this ship. Then as the attacking robber-knights were defeated the emperial battle-ship landed in Duernstein. The emperial soldiers climbed to the castle and fired fire-arrows until the Duernstein Castle was burned down. Today you can only see some destroyed walls on the place were the mighty Duernstein Castle was standing.