Another human civilization may live inside Earth's hollows

So, the theory of the hollow planet was very popular when science was not that advanced as it is now. Mysteries on the surface are not enough for people, and they are constantly looking for new ones inside the Earth. Deeper layers of the lithosphere are the absolute mystery to us, and nobody knows what is located even deeper. There may be lots of unexpected secrets that people dream to uncover.

Ufolog

Translated by Maria Gousseva
Pravda.ru