So-called Jätinkirkko (“the giant’s church”) of Kastelli is a rectangular stone rampart measuring 36 x 62 meters. It dates back to the Stone Age and is one of the most significant ancient structures in Finland. The fort was probably built between 2700-2200 B.C like most of the stone constructions in northern Botnia.
The structure is located at top of the hill. The rampart, which is two meters high in its present state, has six gateways. In the environs are more than twenty rock cairns, a representative group of ten trapping holes and a stone age dwelling site lower on the slope.
Kastelli represents the earliest monumental construction in Finland in a form which is rarely found in hunter-catherer cultures. National Board of Antiques has submitted Kastelli site to the UNESCO Tentative List of World Heritage Sites.
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.