Schlossberg Gützkow

The Schlossberg in Gützkow in the district of Vorpommern-Greifswald is a vacant elevation north of the city center. Gützkow was in the 11th and 12th centuries, an important center and temple of the Slavs. In the 13th and 14th centuries, there was the castle of the Counts of Gützkow. Later there was a castle of the Dukes of Pomerania. Since 1933 the Schlossberg has been under protection, since 1954 a state monument. The Schlossberg is located about 250 meters north of the city center and 280 meters south of the main road 111. East and north runs a stream, the Swinow, through an extensive wetland. From the west the Schlossberg is accessible from the street.
Source: Wikipedia

The castle hill was the seat of the Slavic princes (until about 1200) of the Gützkow counts (1216-1359) and of Duke Barnim VII (1425-1451).
It is an important European ground monument and was excavated in 1930-1934.