Von Daniken!

The Gold of The Gods

When the Spanish chronicler De Cieza described the wealth and power of the
Inca Empire, he deduced that a large portion of the Incan treasure - and population - had been taken to an underground cavern world in the Andes. Treasure hunters have sought the entrances to this purported Incan stronghold over the centuries,
occasionally giving rise to stories of "passages plated with gold" and
forgotten citadels in the Amazon jungle. Erich Von Daniken wrote about such
passages in The Gold of the Gods.

Please look up the book on Amazon, buy it and read it.

Dean