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; a Cold War relic that changed history.

Uncover the secrets of Nazi engineering projects that now lie in ruins. These deserted places are home to extraordinary mysteries and untold secrets, and are revisited to understand how they were built, and why they were abandoned.

This episode is a compilation of segments from S01E01, "Nazi Ghost Town", S01E05, "Soviet Doomsday Device", and S01E04, "Wild West Apocalypse".