An American ghost town in the Amazon jungle, a secret Nazi base, and a deadly concrete fortress 866 miles long are mysterious deserted engineering projects, and new discoveries reveal how they were built and why they were abandoned.

America is the home to strange and incredible engineering projects that now lie in ruins, and new discoveries reveal how they were built and why they were suddenly abandoned. There are cities that are now empty ghost towns, bridges that were never finished, and roads to nowhere. This episode is a mashup of segments from S01E01, "Nazi Ghost Town", S01E06, "The Tesla Conspiracy", and S01E03, "Phantoms Of Chernobyl".