A Skull Found in a Tree, A Deadly Dancer, & Stolen Atomic Bomb Plans: 5 Mysterious Female Spies

A Mysterious President Photo, a Secret FBI Dig, and a Lost Submarine: 5 Unsolved Civil War Mysteries

A Massive Vehicle Under Ice, Unexplained Radio Signals & Pyramids: 5 Unsolved Antarctica Mysteries

The Most Mysterious Person of the Cold War: The Unsolved Case of the Isdal Woman

Mysterious Passengers, An Unexplained Message and Ghost Pilots: 5 Unsolved Aviation Mysteries

An Unexplained Jewel from Space and The Location of Atlantis: 5 Unsolved Ancient Desert Mysteries

5 Unsolved Soviet Mysteries

A Lost Family & Giants of the Wild West: 5 Unsolved Death Valley Mysteries

A Lost Room at the Bottom of the Sea, The Ark Vault and Ben Franklin's Secret: 5 Unexplained Rooms

Sky Trumpets: 5 Frightening Unexplained Sounds from the Sky

Unexplained Cargo, A Foolish Journey and a Boat at the End of the World: 5 Unsolved Mysteries at Sea

The Secret Vatican Time Machine That Photographed Jesus: The Chronovisor

Mysterious Villagers, Metal Alien Spheres and A Lost Island: 5 Unsolved Mysteries of the Arctic

A Ship Stranded in the Desert: 5 Unsolved Mysteries of the Wild West

The Professor Who Fell Through a Rift in Time: The Moberly–Jourdain Time Slip Incident

5 Reddit Posts That Solved Unexplained Mysteries

5 Disturbing Doomsday Plans of the Ultra-Rich

The Mysterious Levitating Statue of Alexandria: 5 Ancient Artifacts That Defied Physics

5 Terrifying Things Humans Have Done to the Earth

The Black-Eyed Children: 5 Most Mysterious Children in History

Skyborne: 5 Mysterious Flying Aircraft Carriers

5 Mysterious CIA Black Sites

Unexplained Islands: 5 Unsolved Island Mysteries

Bricks Made from Astronaut Blood: 5 Strangest Plans To Colonize Mars

The Last Soviet Citizen: 5 People Who Were Last of Their Kind

5 Creepiest Encounters with Extraterrestrials and the Real Men in Black

5 Mysterious Military Lasers and Directed Energy Weapons

Smiled to Death: 5 Terrifying Viruses and Diseases (You Didn't Know About)

True Hell on Earth: 5 Buildings Hiding Terrifying Secrets

3.5-Mile-Tall Tower on the Moon: 5 Mysterious Photos from Space