Some of the world's most incredible engineering projects now lie in ruins. Some of the world's most incredible engineering projects now lie in ruins. These deserted places are home to extraordinary mysteries and untold secrets, and we revisit them to understand how they were built, and why they were abandoned.

Uncovering the secrets of Soviet engineering projects that now lie in ruins; these deserted places are home to extraordinary mysteries and untold secrets, and we revisit them to understand how they were built, and why they were abandoned.

This episode is a compilation of segments from S01E03, "Phantoms Of Chernobyl", S01E01, "Nazi Ghost Town", and S01E05, "Soviet Doomsday Device".