Season 4

Get chills in a bleak communications hub that housed a California cult and then eye a secret US Navy arsenal in Florida.

A crew searches for a shipwreck loaded with gold and sets off a long legal dispute and a lavish complex in the Catskills attracts many of America's great comics.

A company town produces weapons that transform the Wild West and a building complex revolutionizes communications on this world and beyond.

Visit strange structures in New York where Nazis helped launch the US Space Race and then see a New Orleans amusement park where joy turned to despair.

A research facility spawns new technology with earth-shattering implications and a coastal haven for African Americans changes the nation.

The remains of Idaho's nuclear industry mark a new era of American history; a distillery in rural Kentucky revolutionizes liquor; a New England settlement prospers despite prejudice; subterranean chambers produce many of the nation's monuments.

A desert facility trains a nuclear strike force; a church becomes a sanctuary from racial violence; an old military building spawns a creature that haunts a small town.

A brewery in the Pacific Northwest sustains prospectors during the Gold Rush; a Wyoming mining settlement descends into lawlessness; a murder in a small Mississippi town sparks a revolution.

A Military Base trains soldiers in modern warfare to help defeat the Nazis; a suburban basement becomes a major cog in the Detroit bootlegging scene; a brave woman leads a labor union against organized crime.