Mysteries of the Abandoned: Hidden America S04E05 - The Vermont Doomsday Gun

A research facility (Space Research Corporation in Jay, Vermont) spawns new technology with earth-shattering implications;  a coastal haven for African Americans (American Beach, Florida) changes the nation; a forgotten fortress (Fort Greene at Point Judith, Rhode Island) fights off the Nazi submarine U-853; a staunch building (the old San Francisco Mint built in 1874) stands firm on the city's darkest day.