Oddly enough, it appears that there was a "core truth" behind the myth of El Dorado ... only it got blown up way out of perspective in various re-tellings ... there was a South American culture where the King, on certain ceremonial occasions, was coated head-to-toe with gold dust adhered to him with some sort of resin, he would be taken out on a raft into the middle of this lake, and would dive in, washing off the gold, and priests and other officiants would also throw in gold objects and emeralds. Well, this eventually became told as a daily routine, and rather than being part of an otherwise rather ordinary pre-Iron-Age setting, the re-telling built the whole city into gold streets, palaces, etc. The location, amazingly, has even been pretty well determined, and the lake has been drained, dredged, dived in, etc. repeatedly, frequently turning up just enough gold to keep folks coming. Of course, the Spanish fully bought into the "big gold city" thing, and were charging around all over the place, butchering locals who wouldn't tell them where "The Gold City" was, and generally creating massive carnage in the name of their God and Crown.
The first part of the book looks at these various searches, and then it settles in at considering the locals on a rather long scale of 10,000 bce to the 1600's and the post-Conquest chaos. Major sections are given over to discussing the Chavin, the Moche, and the Paracas/Nazca cultures, although attention is also given to the Muisca, the Chimu, the Tiahuanaco, the Wari, and various other groups which preceded the Incas. As much of the traces of these cultures were obliterated by the Spanish, most of what is known of them is pieced together from what burials have not been destroyed by the "professional grave robbers" so prevalent in Latin countries. Fortunately, enough seems to have survived to paint a reasonable picture of each of these groups.
Again, I was surprised by the focus of The Search For El Dorado (I only have 4 of the "Lost Civilizations" series, out of at least 16, and one of the others was about the Incas), and found it very informative in an area that that I had some passing familiarity, but very little in-depth information. These are out of print at this point, so if you'd like a copy, you're looking at the Amazon new/used vendors (or their equivalent elsewhere) ... you can get one for as little as 36¢ (plus shipping) for a copy in "good" condition, and can have a "like new" copy starting around a buck fifty. If this sounds like something you'd like to read up on, I'd certainly tell you to go grab a copy over there!