For decades, the Soviet military limited access to them after the war was over, fuelling speculation about their purpose.
Conspiracy theorists and local folk claimed they were test grounds for Nazi wonderweapons and antigravity devices.
These rings, some said, served as launching pads for Nazi UFOs, flying saucers that used antigravity devices that were later captured by the United States and the Soviet Union.
The machine was so powerful that the project ended with the killing and mass burial of about 60 scientists working on it because, apparently, it makes sense to kill 60 scientists capable of building these machines instead of putting them to work in, say, a bloody nuclear bomb.
Described by a Polish journalist and self-proclaimed military historian based on the alleged testimony of that SS general, the Bell held two counter-rotating 2.5cm thick lead cylinders inside.
The cylinders contained a liquid metal called Xerum 525. It looked like mercury but glowed purple while the machine was powered up using high amounts of electricity.
The concrete rings are located near the village of Liinakhamari, in the region of Murmansk Oblast, Russia, next to Finland.