If you didn't see the movie, you ain't missin' much, but the first 30 seconds of the trailer lays out what Jonsey's looking for in this sequel:

What Indiana's referring to, of course, is Eldorado -- the mythical golden city that British explorer Percy Fawcett disappeared trying to find in the Amazon. Various search-and-rescue parties over the years tried to find Fawcett, but never could; surely evidence that he had connected with and been beamed up by aliens!

But hold your guffaws for just a moment -- what should hit the news cycle today but reports of not one but a series of highly-developed, interconnected, urbanized "lost cities" in a remote part of what was previously thought to be virgin Amazon rainforest! As recently as the 15th century, the Upper Xingu region was home to "a grid-like pattern of settlements connected by roads and centered around large plazas ... now almost completely overgrown by rainforest."

Like ancient Roman and Greek settlements, they were surrounded by large walls, and the inhabitants sustained themselves with a highly-developed form of agriculture. Extensive farms and evidence of wetland management have been discovered nearby, as well as dams and artificial ponds that experts think may be the remains of fish farms. From the BBC:

Professor Mike Heckenberger, from the University of Florida, in Gainesville, said: "These are not cities, but this is urbanism, built around towns."

"They have quite remarkable planning and self-organisation, more so than many classical examples of what people would call urbanism," he said. Although the remains are almost invisible, they can be identified by members of the Kuikuro tribe, who are thought to be direct descendents of the people who built the towns.

The tell-tale traces included "dark earth" that indicated past human waste dumps or farming, and concentrations of pottery shards and earthworks.

The researchers also made use of satellite images and GPS navigation to uncover and map the settlements over the course of a decade.

The communities consisted of clusters of 60-hectare (150-acre) towns and smaller villages spread out over the rainforest.

But so far ... no gold or crystal alien skulls. Unfortunately. But it's enough to make you wonder -- what other secrets is the Amazon hiding?

Archaeologists believe the people who lived there were wiped out by European diseases when colonists began arriving in the 15th century.