http://www.newsweek.com/roundel-prague-europe-7000-years-old-archaeology-1745333

Archaeologists are examining a mysterious monument discovered on the outskirts of Prague that is estimated to be around 7,000 years old—making it even older than Stonehenge and the Egyptian pyramids of Giza.

The ancient monument is being referred to as a roundel—the name archaeologists have given to large circular structures of a similar age that have been found scattered across Central Europe. The shapes and designs of these roundels vary widely, but often they are made up of a complex of trenches divided by a number of entrances. Some of these designs are over 200 meters in diameter.