The Arnstein near Ottendorf is a barely visible medieval rock ruin with a view over the Hintere Sächsische Schweiz.
The Arnstein, also known as Ottendorfer Raubschloss, is located above Ottendorf in the Kirnitzschtal valley. The former fortification was one of the most important castles in the region in the Middle Ages. It later served as a hideout for robber barons and was destroyed in 1451.
Today, remains of the fortifications, a cistern around five meters deep and rock carvings can still be seen. The remains bear witness to the former expansion of the complex and its strategic location.
A marked hiking trail with steps and ladders leads to the castle platform. At the top, there is a wide view of the Schrammsteine, Affensteine and Neuer Wildenstein. The ruins are located in the national park and convey a special atmosphere.