In the eastern area of the Tönsberg there are remains of a fortification from the Germanic period. It is a hill fort from the La Tène period and is considered one of the best-preserved fortifications in Lippe. The mighty ring wall complex is also known as the Saxon camp and was built in the fourth century BC. In the early Middle Ages it offered people from the surrounding area protection and refuge from attacks by enemy hordes. The height of the Tönsberg allowed a good overview of the surrounding country and ensured control over the neighboring passes over which trade routes led to Münster, Paderborn, Lemgo and Hameln. Particularly worth mentioning here is the Wistinghauser Gorge, located on the southeast slope, through which an important trade route ran. The drinking water supply was secured by the Sachsenquelle.
A secure drinking water supply was of great importance for the selection of settlement sites and fortifications. In the area of the eastern Tönsberg, the Sachsenquelle on the upper slope met this criterion. Investigations indicate that the location of the source was moved up the slope into the secured area of the ramparts. A brick-built rectangular collecting basin ensured a sufficient amount of water even in times when there was little rain. Citizens of Oerlinghausen uncovered a former spring house in 1897 in search of water. The spring was given clay pipes and was then used to supply drinking water to the surrounding farms. Sand and tree roots that washed in repeatedly made the pipe unusable, so the water supply via the Sachsenquelle was stopped after the Second World War.
In 2007, the Lippe Biological Station was commissioned to renaturate the Sachsenquelle. During archaeological excavations by employees of the Lippe State Museum, a system of collecting pipes, shafts and overflows were uncovered. During the course of the renaturation, the remains of previous construction work were removed by hand and a natural spring outlet was restored. An existing water treading pool on Tönsbergrundweg will be retained and will be fed by a second spring.
Source: Wikipedia