Ring Wall at Wüstegarten

The remains of a ring wall can be seen on the top of the desert garden. The stone wall is to be seen in the context of the disputes between the Konradines and the Liudolfingian Saxon dukes, initially as late Carolingian counts, then as holders of the royal office under Konrad I. It is highly likely that it dates from the 9th century AD[5] A text panel attached to the desert garden, on the other hand, dates its age to the Iron Age and states that it was used as a fortified place of defense and place of worship.
The oval measures 200 m × 140 m. The rampart, which is still preserved today, is up to 7 m wide in places. In 1963 it was archaeologically examined. It was found that the stones form an external and internal front. Wooden fixtures and superstructures could not be detected. Evidence of a settlement of the place was not found either.
A quartzite block with a hemispherical indentation exhibited in the entrance area of the Jesberg town hall, which was found on the summit plateau, is popularly interpreted as a sacrificial bowl and thus as evidence of a Celtic use of the desert garden as a place of worship or sacrifice. However, there is no evidence of a non-natural origin of the bowl or use of the stone. Finds that indicate the presence of a Celtic population are also completely absent in Lower Hesse.
The desert garden was first mentioned in a document in 1475 as der wuste garten. In the 16th and 17th centuries, the ramparts called Heidelburg were mentioned in writings and documents with the names Heulburgk, Hulnburgk, Hedelberg and Heidelburg.
Source:
de.wikipedia.org/wiki/W%C3%BCstegarten

An old Germanic ring wall is clearly visible here.

The ring wall is very well dated
Kellerwaldturm can be seen