The Nazis built secret megastructures during their bloodthirsty quest for world domination, but today, they're now abandoned; experts are rediscovering these lost places to reveal the mysteries of how they were built and why they were deserted. The segments of this special come from various episodes.

A village on a remote island was once home to the victims of deadly disease, but today, the island and its buildings are abandoned; experts investigate what went wrong in this strange place and what happened to the people who once lived here. The segments of this special come from various episodes.