How the “lost cities” of the Amazon were finally found 

The Amazon has always been one of the most mysterious places on earth.
Lost Cities of the Amazon Discovered From the Air
Mapping technology cut through the canopy to detect sprawling urban structures in Bolivia that suggest sophisticated cultures once existed
When European colonizers arrived in the 16th century, they were captivated by rumors of a golden city, hidden somewhere in the rainforest. Their search for “El Dorado” lasted more than a century, but only resulted in disaster, death, and further conquest of the indigenous people there.
Experts thereafter looked at the Amazon and saw only a desolate jungle; too harsh for extensive agriculture and therefore sparsely populated. They believed that it had always been this way.
Beginning in the late 20th century, archaeologists began looking more closely at the forest floor. Working with the indigenous people who still remained there, they excavated long ditches and mounds. After mapping them, they could see that these were the markings of large settlements; walls, moats, plazas, and roads that connected even more settlements. And they were all over
The Amazon is one of the planet’s last great wildernesses, but legends have circulated for centuries that lost cities existed deep within the forests. A search for El Dorado, a supposed city of gold, lured many Spanish explorers far off the map, and some of them never returned. As recently as the 20th century, British explorer Percy Fawcett searched for what he believed was the Lost City of Z. He vanished into the jungle and added his own unfinished chapter to a tale that began 600 years ago.
Now the plot has taken a new twist, as scientists have discovered that ancient cities really did exist in the Amazon. And while urban ruins remain extremely difficult to find in thick, remote forests, a key technology has helped change the game. Perched in a helicopter some 650 feet up, scientists used light-based remote sensing technology (lidar) to digitally deforest the canopy and identify the ancient ruins of a vast urban settlement around Llanos de Mojos in the Bolivian Amazon that was abandoned some 600 years ago. The new images reveal, in detail, a stronghold of the socially complex Casarabe Culture (500-1400 C.E.) with urban centers boasting monumental platform and pyramid architecture. Raised causeways connected a constellation of suburban-like settlements, which stretched for miles across a landscape that was shaped by a massive water control and distribution system with reservoirs and canals. The site, described this week in Nature, is the most striking discovery to suggest that the Amazon’s rainforest “wilderness” was actually heavily populated, and in places quite urbanized, for many centuries before recorded history of the region began.the Amazon.
References :
The Lost City of Z, David Grann
Exploration Fawcett: Journey to the Lost City of Z, Percy Fawcett
The works of Michael Heckenberger; anthro.ufl.edu/2013/09/29/hec...
Lidar reveals pre-Hispanic low-density urbanism in the Bolivian Amazon www.nature.com/articles/s4158...
The geoglyph sites of Acre, Brazil: 10 000-year-old land-use practices and climate change in Amazonia www.cambridge.org/core/journa...
Predicting pre-Columbian anthropogenic soils in Amazonia royalsocietypublishing.org/do...
The Lore of Lost Cities - Imagining The Lost City Of Z www.forbes.com/sites/davidand...
Once Hidden by Forest, Carvings in Land Attest to Amazon’s Lost World