13 historic monuments, puzzles which are still not solved

The stone balls of Costa Rica

Prehistoric petrosfery with the Pacific coast almost became victims of vandalism: the workers, who found them, they believed that inside the hidden gold. Anyway, artifacts still suffered: to lure tourists, they have established in the urban areas. Due to the constant movement of the exact dating is impossible. The theory of their origin by water was untenable. And, in the end what it is all about: the characters of the planets, signs of borders? The assumptions without evidence.