Two years before the death of Leonardo da Vinci, the aging artist was visited by Cardinal Luigi d'Aragona to survey his works. A diary written by the Cardinal’s secretary suggests da Vinci showcased a Mona Lisa portrait different than the one now on display in The Louvre Museum.

Examine a world wonder so elusive that most people have decided it must be mythical. Centuries of digging have turned up nothing — but the searchers were digging in the wrong place. Now, this film proves that the spectacular Hanging Gardens of Babylon did exist, shows where they were, what they looked like and how they were constructed.

Archimedes of Syracuse is known for inventing a device that efficiently raised water for irrigation. Dr. Stephanie Dalley translated a cuneiform text from of the Assyrian king Sennacherib which led her to believe the Hanging Gardens of Babylon made use of a comparable device approximately 350 years before the time of Archimedes.

Dr. Stephanie Dalley, an expert on the ancient cuneiform texts, is one of a handful of people who can read this language which dates back to the Babylonian era. Her translation of the cuneiform on a prism at the British Museum, leads her to an intriguing theory about the location, builder, and look of the Hanging Garden.

In 146 BC, as the Romans conquered the vast Carthaginian Empire in North Africa, thousands of people fled their homeland. Now, science is suggesting some may have taken refuge thousands of miles away in South America. In addition to the scientific evidence, blonde, blue eyed indigenes suggest that contact with the West occurred long before Columbus arrived.

Countless figures and symbols have been engraved into the monolith since the Itacoatiara culture existed in Rio Paraíba. At an early stage local archaeologists noticed that many of the petroglyphs on the Rock of the Ingá displayed similarities with writing from the Old World in classical times.

Could the Celts and Carthaginians have made it as far Kuelap, the giant fortress built by the Chachapoya?

Dr. David Livingstone is the renowned British explorer, whom American journalist Henry Morton Stanley greeted with the now famous words, “Dr. Livingstone, I presume.” When New York Herald reporter Stanley found him in a small African village on November 10, 1871, the reclusive Livingstone had lost contact with the outside world for six years.

Livingstone charted large parts of the continent previously unseen by European eyes. Where there was once a blank space, he filled in the map of Africa. One of Livingstone’s most famous discoveries was the Victoria Falls on the Zambesi River.

150 years ago, malaria was a mystery to doctors in Africa and the west. On earlier expeditions, when Livingstone travelled along these same river banks, he recorded suffering from malaria dozens of times. Livingstone develops his own medicine and pioneered a systematic dosage to keep him alive. The main ingredient was quinine, found in the bark of the South American cinchona tree.

Fifty years after the tragic shooting of President John F. Kennedy, Secrets of the Dead chronicles minute-by-minute the assassination as it was revealed in the CBS newsroom from the moment the President was shot until Walter Cronkite's emotional pronouncement of his death, one hour and eight minutes later.

The mystery surrounding the bones of the Buddha dates back more than 100 years ago, when colonial estate manager William Peppe and his workers began digging at a mysterious hill in Northern India. Peppe had no idea what they'd find just a little more than 20 feet down. They unearthed an astonishing discovery: a huge stone coffer, containing five reliquary jars, more than 1,000 separate jewels.

In 1922, in Egypt's Valley of the Kings, archaeologist and Egyptologist Howard Carter made the greatest archaeological find in history: the discovery of Tutankhamun's tomb and its golden treasures worth nearly a billion dollar. Carter’s find made Tutankhamun the most famous pharaoh in ancient Egyptian history. But the real story of King Tut has become shrouded in myth.

A tomb of 49,000 year-old Neanderthal bones discovered in El Sidron, a remote, mountainous region of Northern Spain, leads to a compelling investigation to solve a double mystery: How did this group of Neanderthals die?

Less than two months after 57 Irish immigrants were hired to lay railroad track in Pennsylvania in 1832, all were dead. Were they victims of a cholera epidemic or something much darker?

Spied upon by MI19 in a bugging operation of unprecedented scale and cunning, 4,000 German POW’s revealed their inner thoughts about the Third Reich and let slip military secrets that helped the Allies win WWII.

Fifty years ago, in October 1962, the world teetered on the brink of nuclear war. This is the little-known story of how close to nuclear destruction the world really was during those dark October days, and how the heroism of one man saved us all.

Beginning in the 1950s, American and Soviet scientists embarked on a perilous race to see who could build and detonate the world’s largest bomb. The results exceeded all expectations about how big a bomb could be built. Initially, the Americans led the way, but then left the field clear for the Soviet Union to break all records.

The extraordinary story of China's 8,000 terracotta warriors begins two centuries before the birth of Christ. The First Emperor of China was preparing an extravagant tomb for his journey into the afterlife — and decreed that he be protected forever by a monumental army.

A modern day quest to find the truth behind one of exploration's greatest mysteries: What happened to famed adventurer Col. Percy Fawcett who went looking for a city of gold — the Lost City of "Z" — in the Amazon in 1925 and disappeared in the jungles of Brazil forever?