Deep in the Amazon jungle, a team of explorers has stumbled upon ruins that are forcing us to rethink everything we know about ancient civilizations.
Hidden beneath a layer of centuries-old vegetation were pyramids larger than those in Egypt, and a system of canals that testified to advanced engineering.
Scientists have discovered artifacts resembling electric batteries - clay vessels with copper rods and traces of acid.
Experiments showed that such devices could generate current sufficient for gilding jewelry.
Even more mysterious were the frescoes depicting star clusters that cannot be seen without a telescope.
How did people living thousands of years ago know about the existence of the Orion Nebula?
Symbols similar to modern mathematical formulas, including the number π to five digits, have been found on temple walls, casting doubt on the theory that ancient civilizations did not possess complex calculations.
But the main find was stone slabs with maps pointing to other cities that had not yet been discovered.
Satellite images have confirmed that there are indeed structures underground that resemble streets and buildings.
We may be on the verge of discovering a whole network of ancient cities that were linked by trade routes.
Soil analysis revealed traces of plants that did not grow in the region, indicating that the city's inhabitants were engaged in selection or had contacts with the continents across the ocean.
Who were they? Local tribes' legends speak of "people from the sky" who taught them agriculture and disappeared after the wrath of the gods.
Scientists can't answer that yet, but one thing is clear: human history is far more complex than we thought. Our ancestors may have had technologies we're only just beginning to understand.
