After abandoning the Alblimes (a Limes generally following the ridgeline of the Swabian Jura) around 150 AD, Aalen's territory became part of the Roman Empire, in direct vicinity of the then newly erected Rhaetian Limes. The Romans erected a castrum to house the cavalry unit Ala II Flavia milliaria; its remains are known today as Kastell Aalen. The site is west of today's town centre at the bottom of the Schillerhöhe hill. With about 1,000 horsemen and nearly as many grooms, it was the greatest fort of auxiliaries along the Rhaetian Limes. There were Civilian settlements adjacent along the south and the east. Around 260 AD, the Romans gave up the fort as they withdrew their presence in unoccupied Germania back to the Rhine and Danube rivers, and the Alamanni took over the region. Based on 3rd- and 4th-century coins found, the civilian settlement continued to exist for the time being. However, there is no evidence of continued civilization between the Roman era and the Middle Ages.
There is a Limes Museum located adjacent the Kastell.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.