First mentioned in historic documents in 1254, Burg Groppenstein was built in a particularly beautiful place, where the River Mallnitz flows into the River Möll. In the 15th century it was turned into a defence in the style of the late Middle Ages. In 1872 the castle was renovated by the Viennese architect Adolf Stipperger, and its exterior design has since been unchanged.
The Romanesque wing was replaced by Gothic dwellings and weirs with towers and battlement walls. The Knights Hall features beautiful, 16th century stained glass windows. Other glass paintings were added by Prof. Franz Chvostek, who owned the castle from 1936 to 1944.
Also worth a visit is the castle chapel consecrated to St. Katharina with its gothic aisle and semi-circular Romanesque apse.References:
The Externsteine (Extern stones) is a distinctive sandstone rock formation located in the Teutoburg Forest, near the town of Horn-Bad Meinberg. The formation is a tor consisting of several tall, narrow columns of rock which rise abruptly from the surrounding wooded hills. Archaeological excavations have yielded some Upper Paleolithic stone tools dating to about 10,700 BC from 9,600 BC.
In a popular tradition going back to an idea proposed to Hermann Hamelmann in 1564, the Externsteine are identified as a sacred site of the pagan Saxons, and the location of the Irminsul (sacral pillar-like object in German paganism) idol reportedly destroyed by Charlemagne; there is however no archaeological evidence that would confirm the site's use during the relevant period.
The stones were used as the site of a hermitage in the Middle Ages, and by at least the high medieval period were the site of a Christian chapel. The Externsteine relief is a medieval depiction of the Descent from the Cross. It remains controversial whether the site was already used for Christian worship in the 8th to early 10th centuries.
The Externsteine gained prominence when Völkisch and nationalistic scholars took an interest in the late 19th and early 20th centuries. This interest peaked under the Nazi regime, when the Externsteine became a focus of nazi propaganda. Today, they remain a popular tourist destination and also continue to attract Neo-Pagans and Neo-Nazis.