Die Glocke

Brief history:
Die Glocke ("The Bell") was a purported top-secret Nazi scientific technological device, secret weapon, or Wunderwaffe. First described by Polish journalist and author Igor Witkowski in Prawda o Wunderwaffe (2000), it was later popularized by military journalist and author Nick Cook who associated it with Nazi occultism, antigravity and free energy research. Mainstream reviewers have criticized claims about Die Glocke as being pseudoscientific, recycled rumors, and a hoax. Die Glocke and other alleged Nazi "miracle weapons" have been dramatized in video games, television shows, and novels.

Source: en.wikipedia.org/wiki/Die_Glocke