Hollywood's favorite archaeologist has chased around Egypt, India, the Middle East ... and the Amazon as well. "Indiana Jones and the Kingdom of the Crystal Skull" is loosely inspired by a supposed Mesoamerican legend that 13 widely dispersed crystal skulls will yield unprecedented powers when united.
In real life, several purported crystal skulls are housed in museums around the world, though archaeologists doubt their ancient provenance and mystical powers. Instead, these skulls are primarily seen as fakes sold by 19th-century antiquities dealers to feed a market hungry for pre-Hispanic relics. Nevertheless, the archaeological mystery of the crystal skulls lives on. Skull hunters still search for them, and the Maya believe they hold special powers. In this picture, a priest hoists a skull in a ceremony at the Palenque ruins in Mexico.
Click the "Next" arrow above to learn about six more archaeological mysteries.
— John Roach, msnbc.com contributor
Where is the grave of Genghis Khan?
Where is Genghis Khan buried? Nobody knows. The bloody Mongol warrior became famous as the ruler of an empire that eventually stretched from China to Hungary, but he asked to be buried in an unmarked grave. According to legend, anyone who witnessed the burial party en route to the funeral in 1227 was killed, and then the soldiers and servants who attended the funeral were massacred. Thus, the grave site has been one of archaeology's enduring mysteries. But scientists may be closing in on the location at last. In 2004, they unearthed the site of Genghis Khan's 13th-century palace, which is pictured here. Ancient texts suggest the grave itself could be nearby.
What happened on Easter Island?
Hundreds of monolithic statues called Moai, including the ones in this picture, ring remote Easter Island in the South Pacific. They face inland from the shore, presumably keeping watch over ancestral lands. Scientists unraveling the mystery of how the Polynesian settlers moved the statues are also piecing together the tale of the settlers' demise. According to a leading theory, giant palms were hacked down to roll the statues into place beginning in about 1200. As the population swelled, more chiefs requested statues, and more trees were felled. Eventually the island was denuded. Easter Island's environment — and society — collapsed. Other researchers pin the blame on Europeans, disease and rats.
Was Stonehenge a place of healing?
Every year at the summer solstice, thousands of people witness the season's first sunrise at Stonehenge, about 90 miles west of London in the English countryside. Was the monument erected beginning around 3000 B.C. for the secular purpose of marking time? Perhaps, some scholars say. Another prominent theory suggests it was a place of worship. The most recent idea holds that the monument was erected as center of healing. Archaeologists dug at the site for the first time in nearly half a century to get a precise date for Stonehenge's bluestones, which were thought to have healing powers. A close match with the time frame during which archaeologists believe the stones were taken from the Perseli Mountains, 153 miles away, could help confirm the theory.
Why were the Nazca Lines etched?
Hundreds of lines and figures etched into the coastal desert of southern Peru have baffled archaeologists for decades. The Nazca people made the playing-field sized etchings between 200 B.C. and A.D. 700 by removing rust-colored pebbles to reveal the lighter soils beneath. Some are simple shapes reminiscent of geometry class. Others are recognizable animals, such as the hummingbird in this image. But what do they mean? Theories proposed over the years have ranged from religious and astronomical purposes to guideposts of sorts for finding water.
What is China's terracotta army guarding?
In 1974, archaeologists found an army of thousands of terracotta statues standing guard outside the tomb of Qin Shi Huang Di, the ruler who unified China in 221 B.C. The find ranks as one of the greatest archaeological discoveries of the 20th century. Each of the soldiers has a unique facial expression, and the troops are aligned according to rank in trenchlike corridors, accompanied by horses and chariots.
As impressive as the army may be, scientists suspect that even greater treasure lies within Qin's unexcavated tomb. An account by an ancient court historian suggests that the tomb is full of miniature palaces, rivers of mercury and precious stones to represent the moon and stars. Remote sensing and nearby excavations have lent some credence to the writings.
How were the Egyptian pyramids built?
The Great Pyramid of Giza near Cairo, one of the ancient Seven Wonders of the World, retains its world-famous status in a 21st-century list of seven wonders. Its mystique partly rests in just how the 479-foot-tall burial structure was built. Most Egyptologists believe large stones were moved from a quarry and lifted into place, but how? Teams of workers could have dragged the 2.5-ton stones with brute force, or perhaps they rolled them on logs. However they did it, recent research suggests the workers were skilled, not untrained slaves.