When experts investigate ancient tunnels rumored to be the hiding place of lost royal treasure, they find evidence of human sacrifice for the Viking god Odin. An abandoned fortress in Siberia sheds new light on Genghis Khan.

New evidence may reveal the location of Hitler's lost billion-dollar gold train. A long-lost settlement rewrites the history of the Vikings in North America. A blood-red river in Siberia points to catastrophic pollution.

An ancient man-made volcano might reveal buried treasure and human sacrifice. When NASA discovers a strange pattern in the Arctic ice, experts wonder if it has alien origins. A mystery in the Sahara may have a sinister explanation.

Man-made islands are spotted near a North Korean missile facility. When something unexpected is found in a remote desert, experts investigate a lost city of giants. A strange discovery in Siberia could reveal a mission to the center of the earth.

An abandoned city in the African jungle might have a bloody past of malevolent spirits and cannibals. Mount Vesuvius shows signs that it's awakening, and the mafia could be to blame. Experts investigate Hitler's secret Nazi UFO program.

Experts investigate a glowing lake reported to turn things into stone. A mysterious structure in Africa that resembles Stonehenge is said to be the resting place of a mythical giant. A dark conspiracy could be at work in the Australian outback.

A mysterious Stonehenge-like structure in Russia might have links to the Nazis. Experts uncover clues to a mega-tsunami with the power to devastate the United States. A huge lake appears in the Sahara overnight, and its explanation could be mythical.

New discoveries lead investigators to a crypt rumored to hold the Ark of the Covenant. When great white shark is killed, experts suspect an mysterious ocean monster. Strange markings in the desert might be a tribute to an ancient spider god.

Treasure hunters have searched for a lost Incan city of untold wealth for a century, but new technology might finally locate its riches. A strange mountain in Egypt sparks an investigation into Cleopatra's gems and the tomb of Alexander the Great.

A ghost ship is found abandoned on a remote island that's home to one of the world's last uncontacted tribes. A strange labyrinth in Sicily might have a sinister connection to the Mafia. New evidence reveals a mysterious military compound in Russia.

Something strange in the Himalayas could be evidence of a top-secret CIA program to turn monks into killer agents, and cutting-edge science helps experts investigate the truth behind this mysterious anomaly.

Some of the world's most incredible engineering projects are now deserted. Revisit a Soviet megastructure, a massive Nazi brainwashing complex, and a dangerous desert pass. How were they built? Why were they mysteriously abandoned?

Some of the world's most incredible engineering projects are now deserted. Explore a ghost town that was once a dangerous industrial hellscape, a giant warship at the bottom of the ocean, and a top secret relic from the Cold War.

Some of the world's most incredible engineering is now deserted. Explore what happened to the town located outside of Chernobyl on the eve of disaster, a fleet of ghost ships, and a dangerous mountain road that changed history.

Some of the most incredible engineering projects, now deserted. Explore what happened to a military site that was once a hotbed for nuclear testing, a top secret airbase hidden inside a mountain, and an otherworldly power plant.

Some of the world's most incredible engineering projects are now deserted. See what happened to a classified Soviet machine built to prevent nuclear war, a top secret Nazi facility, and a strange tower that left an enduring legacy.