Neolithic circular enclosures in Central Europe
Approximately 120–150 Neolithic earthworks enclosures are known in Central Europe. They are called Kreisgrabenanlagen ("circular ditched enclosures") in German, or alternatively as roundels (or "rondels"; German Rondelle; sometimes also "rondeloid", since many are not even approximately circular).
Source: Wikipedia — Neolithic circular enclosures in Central Europe (CC BY-SA 4.0)