Ancient peoples across the Americas created large, complex societies that have only recently come to light through new technologies. Archaeological research using lidar, a laser-based scanning method that can map terrain beneath dense vegetation, has revealed evidence of extensive civilizations in the Amazon rainforest and other regions. These discoveries are changing how scientists understand the scale and sophistication of pre-Columbian societies.
In the Amazon, evidence points to the Akiri, a civilization that may have numbered up to three million people at its height around 1,500 years ago. They built earthworks across a large area of southwestern Amazonia in what is now Brazil, Bolivia, and Peru. The structures, which included circles, squares, octagons, and other geometric shapes, were carved from the ground using ditches and raised earth. Some covered more than a hundred acres. Researchers estimate that between 23,000 and 30,000 such features may still lie hidden beneath the forest, with roughly 1,700 documented so far.
Earlier estimates suggested around 450 earthworks existed in this region. The new figures come from lidar surveys that scanned an area covering less than 3% of the Amazon. These scans allowed researchers to map the ground surface after digitally removing the forest canopy. Most earthworks appear to have been gathering places used for ceremonies, meetings, and ball games, rather than permanent residential sites. People likely lived in nearby longhouses shared by several families.
The Akiri probably emerged around 600 B.C.E. and built these structures without metal tools or draft animals. Researchers believe each structure required roughly 300 people to build and maintain. The civilization appears to have abandoned its earthworks between 850 and 950 C.E., though the cause remains unclear. Some researchers see a possible connection to the broader decline of other ancient American civilizations, such as the Maya, but no consensus exists.
A separate finding in the Bolivian Amazon has uncovered traces of the Casarabe culture, which thrived roughly between 500 and 1400 C.E. Lidar surveys around the Llanos de Mojos region identified 26 settlements, including 11 previously unknown sites. Two of the largest urban centers covered about 1.5 square miles each and featured earthen platforms, pyramids reaching roughly 70 feet in height, and surrounding moats and ramparts. Networks of raised causeways and canals connected settlements across the landscape and linked them to rivers and lakes. The Casarabe also created fertile soil by mixing charcoal, bone, and organic waste into the rainforest soil, allowing them to farm maize and other crops on a large scale. Their decline may have been linked to a severe drought, though no single explanation has been confirmed.
The search for ancient Amazonian cities has a long history. British explorer Percy Fawcett disappeared in 1925 while searching for a city he called Z. His expedition, along with his son and a companion, was never found. In 2016, the story became a film based on a 2009 book. Modern lidar surveys have since given researchers new tools to explore the same regions Fawcett sought. Recent fieldwork in the Amazon has also involved ground teams checking lidar data directly, with researchers trekking through dense jungle and facing difficult conditions.
Evidence of earlier complex societies has also emerged elsewhere in the Americas. In Peru, the Caral civilization flourished roughly 5,000 years ago along the north-central coast. This society built stepped pyramids, sunken plazas, and other large structures across more than 30 metropolitan centers. The site of Pequi, located about 115 miles north of Lima, has been under excavation for about eight years. Teams have uncovered temples, residential buildings, and a large circular plaza. Archaeologists have found clay sculptures, stone tools, and shell trumpets at the site. No evidence of conflict has been found at Caral sites, and researchers generally regard this society as relatively peaceful. Its decline likely came from environmental factors, such as prolonged drought, rather than a single catastrophic event.
In the United States, the Alpena-Amberley Ridge in Lake Huron preserves a submerged prehistoric landscape. Two obsidian flakes recovered from the site in 2013 came from central Oregon, roughly 2,500 miles away. The flakes are thought to be about 10,000 years old and suggest long-distance trade networks in the region at that time. Researchers have also found preserved trees and peat bogs in the area, which are helping them understand the environment of the time.
Ancient construction sites continue to raise questions. At Tiwanaku in Bolivia, the site of Puma Punku contains massive stone blocks carved with precision that some researchers find difficult to explain using known ancient technologies. The largest blocks weigh more than 130 tons, and the builders used both red sandstone and andesite, one of the hardest rocks available. Some blocks fit together like puzzle pieces with straight angles and drilled holes. No record exists of the tools used. The builders moved the stones from quarries without wheels or draft animals. While the Tiwanaku culture is generally credited with the construction, the exact methods used remain unresolved. Some theories, including claims of extraterrestrial involvement, lack scientific support. A UCLA research team created a 3D model of the site and concluded that humans built it, comparing its style to other structures in the region.
In Lebanon, the temple complex at Baalbek includes some of the largest worked stones known. A foundation block found in a quarry there weighs more than 1,000 tons, with another block discovered in 2014 weighing approximately 1,650 tons. Researchers have not determined how these stones were moved or lifted, though existing theories involve ropes, winches, and ramps. In Egypt, the Serapeum of Saqqara contains granite sarcophagi weighing 70 to 100 tons, cut with smooth surfaces and precise symmetry. Some scientists have noted that even modern technology would struggle to replicate this work.
Other unexplained artifacts include the 100-ton stone blocks at Puma Punku, which were transported over 40 miles to an altitude of nearly 12,600 feet; the Lycurgus cup, whose glass changes color due to embedded nanoparticles of gold and silver; and the iron pillar of Delhi, which has resisted corrosion for about 1,600 years. The Longyou Caves in China, carved into rock, were discovered in 1992 after a village pond was drained. The caves include galleries, pools, and columns, but no records of their construction have ever been found.
In the Philippines, the Chocolate Hills provide a natural parallel to questions about artificial construction. These 1,200 to 1,700 symmetrical mounds likely formed through the erosion of limestone over thousands of years. Local legends offer alternative explanations involving giants and lost loves. Similarly, Cerro El Cono in the Peruvian Amazon is a perfectly cone-shaped mountain that some have theorized could be an ancient pyramid. Geologists suspect it may be a volcanic formation, but no formal confirmation exists.
In Japan, the Yonaguni Monument sits underwater off the coast of the Ryukyu Islands. The structure consists of layered platforms, steps, and sharp edges that some believe were shaped by human hands. Others argue that natural geological forces, such as earthquakes and ocean currents, could explain the formations. A marine geologist has reported finding carved marks and animal-shaped rocks, but the site remains contested among researchers.
On the Greek coast, the submerged city of Pavlopetri dates back roughly 5,000 years. It was first mapped in the 1960s and studied in greater detail starting in 2009. The ruins include buildings, streets, courtyards, and tombs, and may have housed between 500 and 2,000 people at its peak. Scientists believe it sank after an earthquake, though the exact cause is uncertain. Some researchers have suggested Pavlopetri as a possible inspiration for the Atlantis myth.
The island of Crete, meanwhile, is known for the Minoan civilization, which built elaborate palaces such as Knossos during the Bronze Age. The complex design of these buildings, including multiple stories and intricate hallways, may have inspired the later Greek legend of the labyrinth and the Minotaur.
The Indus Valley civilization, also called the Harappan civilization, reached a high level of urban development around 4,500 years ago. Cities such as Harappa and Mohenjo-daro had baked brick homes, drainage systems, and public baths. The civilization engaged in trade across the Middle East and created standardized weights and seals for commercial use. Its script remains undeciphered, and the reasons for its decline around 1800 B.C.E. likely involved environmental changes such as shifting river patterns.
In South Africa, skull fragments found in 1913 point to a species sometimes called Boskop man, which may have had larger brains than modern humans. Some researchers have estimated its IQ at around 149, though this claim is disputed and largely speculative. If such a species existed, it may have lived as recently as 10,000 years ago. No clear explanation exists for its disappearance.
An Egyptian pylon at Karnak and the animal mummies of the Serapeum add to the list of ancient sites built with exceptional effort and precision, often beyond what would have been necessary for their apparent purpose. The Apis bulls, considered sacred by the ancient Egyptians, were buried in granite sarcophagi weighing up to 100 tons, despite the enormous cost of quarrying and transporting the material.
A shipwreck recounted in Spanish records involved a fleet that sank in a hurricane in 1622 near the Florida Keys, losing a large cargo of gold and silver. The Spanish mounted a salvage operation that recovered some treasure but failed in most cases. In the 1970s, diver Mel Fisher began a long effort to locate the wreck. After 16 years of searching, his team found the wreck of the Atocha and some of its cargo, including gold, silver, and other artifacts. The story became widely known in popular culture.
Across these sites, the common thread is the limited knowledge researchers still have about the full extent of ancient societies. Lidar is helping to map terrain hidden under forest cover, but these surveys remain expensive and time-consuming. Scholars still debate the scale of Amazonian settlement and the causes of decline for civilizations like the Akiri and Casarabe. Most researchers expect that additional discoveries will be made as mapping tools improve and fieldwork continues.
Scientists are also developing methods to study submerged sites in the Great Lakes and elsewhere, using sonar and underwater robots to document structures that have been preserved in water for thousands of years. DNA analysis of materials recovered from such sites may help clarify the animal and plant life of the period.
The mysteries of uninhabited regions and the ruins beneath them continue to attract attention, but the questions remain set within the limits of current archaeological data. What seems clear is that the Americas contained multiple large and organized societies long before European contact, and that the forest canopy has obscured a significant portion of that record from view. Researchers continue to explore the possibility that large populations lived in the Amazon before the arrival of Europeans, and that earlier assumptions about the rainforest being a primal wilderness are incomplete projections of modern observers.
