A look at megastructures, including Mexico's Olmec heads, Easter Island's moai statues, Jordan's ancient city of Petra and Armenia's Geghard monastery.

A look at mysterious writings, images and relics, including Peru's Nazca Lines geoglyphs, the Voynich manuscript and China's Terracotta Army.

Searching for the truth amidst the hidden identities of historical figures such as Jack the Ripper, D.B. Cooper, and the Man in the Iron Mask.

A look at paranormal phenomena, including ghosts, apparitions and spectral curses.

A look at sites with alleged healing powers, including the grotto of Lourdes, Peru's ancient Machu Picchu ruins and the Amazon rainforest.

Exploring significant religious sites across the globe, including South Dakota's Black Hills and a monastery in Catalonia.

A look at sacred texts, including the Bible, the Book of the Dead and the Tao Te Ching.

A look at extraordinary abilities, incuding extreme strength and endurance, telepathy, clairvoyance and paranormal empathy.

A look at revered religious artifacts, including the Holy Grail, Buddha's Tooth, the Ark of the Covenant and the Shroud of Turin.

A look at scientific mysteries, including water memory, morphic fields, time travel, the placebo and nocebo effects, and virtual reality matrices.

A look at extraterrestrial mysteries, including close encounters, crop circles, Area 51, ancient texts and UFOs.

Analyzing notably enigmatic artwork such as da Vinci's "Last Supper", "Girl with a Pearl Earring", and a crucifixion icon with real teeth

A look at ancient and unorthodox medical treatments from regression therapy to herbal supplements.

Assessing unusual cases of people who vanished without a trace, including an explorer, a British secret agent, and an entire family.

Exploring the unanswered questions of the Second World War, such as Raoul Wallenberg's fate and who betrayed the family of Anne Frank.

Tracing the origins of mummification in cultures beyond Egypt, as well as delving for answers to unresolved mysteries behind the practice.