Investigating mysteries that elude scientific explanation.

Unsolved urban mysteries include a walrus skeleton found in a mass London grave, Moscow's secret Metro line and Prague's occult origins.

Individuals whose identities remain a mystery including D.B. Cooper, Jack the Ripper and the Man in the Iron Mask.

Classified military projects from false flag operations to America's recruitment of Nazi scientists after World War II.

Locations around the world with special religious significance from a Catalonian monastery to South Dakota's Black Hills.