Hidden in the Nevada desert, a top-secret military base remains one of the most heavily restricted sites in the United States; since the 1950s, speculation has swirled about its true purpose-ranging from hiding experimental aircraft and even alien technology; Area 51 keeps its mysteries so closely guarded that not even the president is fully briefed; what is the government really hiding there?

Hidden in the Nevada desert, a top-secret military base remains one of the most heavily restricted sites in the United States; since the 1950s, speculation has swirled about its true purpose-ranging from hiding experimental aircraft and even alien technology; Area 51 keeps its mysteries so closely guarded that not even the president is fully briefed; what is the government really hiding there?

At the end of World War II, many Nazi officials were captured and tried for their crimes. But one of the architects of the Holocaust, Adolf Eichmann, slipped through the cracks…repeatedly eluding Nazi hunters from around the globe.

At the end of World War II, many Nazi officials were captured and tried for their crimes. But one of the architects of the Holocaust, Adolf Eichmann, slipped through the cracks…repeatedly eluding Nazi hunters from around the globe.

It's one of humanity's oldest nightmares-at the full moon, werewolves that once were men hunt human prey and then feast on their flesh. Stories of this terrifying transformation persist to this day.

It's one of humanity's oldest nightmares-at the full moon, werewolves that once were men hunt human prey and then feast on their flesh. Stories of this terrifying transformation persist to this day.

The world's most famous painting vanishes in a daring heist, sparking international outrage and a global manhunt. A master detective is called in, who zeroes in on a handful of suspects with the motive and means to pull off the theft. Who stole the legendary Mona Lisa?

The world's most famous painting vanishes in a daring heist, sparking international outrage and a global manhunt. A master detective is called in, who zeroes in on a handful of suspects with the motive and means to pull off the theft. Who stole the legendary Mona Lisa?

It’s one of the most legendary monsters said to be lurking in the vast open seas. With stories going back hundreds of years, this elusive creature has terrorized sailors and baffled scientists.

It’s one of the most legendary monsters said to be lurking in the vast open seas. With stories going back hundreds of years, this elusive creature has terrorized sailors and baffled scientists.

The notorious mafia kingpin, Sam Giancana, is shot execution style in his own home. The larger-than-life mobster had many enemies, from inside the mafia to the CIA.

The notorious mafia kingpin, Sam Giancana, is shot execution style in his own home. The larger-than-life mobster had many enemies, from inside the mafia to the CIA.

A twisted mastermind uses homemade bombs to terrorize the nation. Despite one of the most extensive manhunts in U.S. history, he still manages to stay one step ahead of law enforcement for nearly two decades.

A twisted mastermind uses homemade bombs to terrorize the nation. Despite one of the most extensive manhunts in U.S. history, he still manages to stay one step ahead of law enforcement for nearly two decades.

A series of shocking murders shake the city of Boston to its core. Each victim, 13 women in all, bore the signature of this serial killer.

A series of shocking murders shake the city of Boston to its core. Each victim, 13 women in all, bore the signature of this serial killer.

A shot rings out from the balcony of the Ford's Theater in Washington, D.C. and America's 16th president has been killed. Who was behind the plan to assassinate President Lincoln?

A shot rings out from the balcony of the Ford's Theater in Washington, D.C. and America's 16th president has been killed. Who was behind the plan to assassinate President Lincoln?

El Chapo is an untouchable drug lord who sat atop a criminal empire and became the most wanted man in the world. How did investigators finally bring El Chapo to justice?

El Chapo is an untouchable drug lord who sat atop a criminal empire and became the most wanted man in the world. How did investigators finally bring El Chapo to justice?

Bruce Lee was a seemingly invincible icon and the closest thing that we had to a real-life superhero. What killed him?

Bruce Lee was a seemingly invincible icon and the closest thing that we had to a real-life superhero. What killed him?

Known for their seafaring skills and feared for their ferocity, the Vikings amassed gold, silver and other riches while trading and raiding across Europe; catches of this treasure have been found in Europe and North America, but this may be just the tip of the iceberg; are there any rich Viking hoards still waiting to be found? And if so, where are they?

Known for their seafaring skills and feared for their ferocity, the Vikings amassed gold, silver and other riches while trading and raiding across Europe; catches of this treasure have been found in Europe and North America, but this may be just the tip of the iceberg; are there any rich Viking hoards still waiting to be found? And if so, where are they?

On December 11, 1978, a gang of thieves lift around $5 million in cash and $800,000 in jewelry from a luxury airline hangar at New York's JFK Airport, marking the largest heist in U.S. history at that time.

On December 11, 1978, a gang of thieves lift around $5 million in cash and $800,000 in jewelry from a luxury airline hangar at New York's JFK Airport, marking the largest heist in U.S. history at that time.

During World War II, a fiery phenomenon terrorizes American airmen in the night skies over Europe. The pilots call these fireballs "Foo Fighters," and swear they move at over 200 mph and defy the laws of physics. But what are they?

During World War II, a fiery phenomenon terrorizes American airmen in the night skies over Europe. The pilots call these fireballs "Foo Fighters," and swear they move at over 200 mph and defy the laws of physics. But what are they?

General Erwin Rommel captured territory, imprisoned local Jews in camps, and stole their gold and valuables in the name of the Führer. For decades, many have looked for this elusive treasure. What became of Rommel's gold?

General Erwin Rommel captured territory, imprisoned local Jews in camps, and stole their gold and valuables in the name of the Führer. For decades, many have looked for this elusive treasure. What became of Rommel's gold?

When the British Red Coats march into Lexington in 1775 prepared for a surprise attack, they are met with a small scrappy militia ready for a fight; it's the battle that kicked off the American Revolution, but centuries later, two questions remain: Who warned the Patriots that the British were coming and who fired the shot heard round the world?

When the British Red Coats march into Lexington in 1775 prepared for a surprise attack, they are met with a small scrappy militia ready for a fight; it's the battle that kicked off the American Revolution, but centuries later, two questions remain: Who warned the Patriots that the British were coming and who fired the shot heard round the world?

As one renowned military leader, his conquests were so decisive that some believed he was descended from the gods; at only 32, with a vast empire that was rapidly expanding, Alexander the Great died unexpectedly; what, or who, is responsible for the death of Alexander the Great?

As one renowned military leader, his conquests were so decisive that some believed he was descended from the gods; at only 32, with a vast empire that was rapidly expanding, Alexander the Great died unexpectedly; what, or who, is responsible for the death of Alexander the Great?

In the final days of the Civil War, Confederate leaders fled south, rumored to be carrying the Confederate treasury worth an estimated $13 million in today's money. But when Jefferson Davis is captured, there's no treasure in his baggage. Where did the stolen money end up… and could it still be out there, waiting to be found?

In the final days of the Civil War, Confederate leaders fled south, rumored to be carrying the Confederate treasury worth an estimated $13 million in today's money. But when Jefferson Davis is captured, there's no treasure in his baggage. Where did the stolen money end up… and could it still be out there, waiting to be found?

Deadly anthrax spores sent through the mail kill five people and spread authorities thin. The FBI works around the clock to stop this brazen act of bioterrorism, but the letters keep coming.

Deadly anthrax spores sent through the mail kill five people and spread authorities thin. The FBI works around the clock to stop this brazen act of bioterrorism, but the letters keep coming.

Using new evidence to look at some of the most historically important mysteries of recent times.

Using new evidence to look at some of the most historically important mysteries of recent times.