A fortified structure consisting of concentric features was noticed by aerial archaeologist near Oława, South Poland. The researchers believe the structure may be 7000 years old.
A series of concentric cropmarks, indicating the possible presence of a rondel-like structure, has been sighted at Żelichów, North-West Poland. This find is extremely rare as only a handful of such Neolithic structures are known from Poland.
A monument in Avebury, England, consisting of two huge, circular enclosures, was discovered being about 5300 years old, meaning the structure pre-dates the first stones erected at nearby Stonehenge by about 800 years.