the omphalos, an ancient religious stone artifact marking the center of the world

rock ruins grave monument wall headstone cemetery memorial sculpture stonewall garden art boulder statue temple stones god archaeology world earth historical tholos column historic europe doric tourism navel stone oracle sanctuary ruin old travel mountain antique archeology apollo religion nature myth market landscape landmark history hellenic greek greece grass delphic delphi delfi culture construction classical center brick artifacts artifact architecture archaeological ancient omphalos religious marking according greeks unesco heritage site greece