Underground Sydney is explored. Included: a 19th-century prison; caves that were once home to fugitive outlaws; gold mines. Also: a secret World War II storage place for chemical weapons is toured by those who once worked there.
Underground Cairo is explored, focusing on ancient structures that have withstood time and countless invasions. Included: a step pyramid built a century before the Giza pyramids; and a tomb containing 2000-year-old mummies. Also examined: the Book of the Dead.
Underground Ethiopia is explored. Included: tombs of emperors; subterranean cathedrals; and the palace of the Queen of Sheba. Also: theories regarding the possible resting place of the Ark of the Covenant.