Abandoned engineering projects include a classified Soviet machine built to prevent all-out nuclear war, a top-secret Nazi facility, and a strange tower that left an enduring legacy.

Some of the world's most incredible engineering projects are now deserted; Explore what happened to a cutting-edge research complex built by a visionary genius, an ambitious Nazi project that met a sinister end, and a Cold War relic that changed history.

A strange Cuban prison, an eerie escape route built for Armageddon, and an underwater marvel that changed history are mysterious deserted engineering projects, and new discoveries reveal how they were built and why they were abandoned.