Video footage captured in Gothenburg, Sweden, shows the bizarre scenes that commuters were faced with on November 6.
As drivers looked into the sky, a strange “bell-shaped” object could be seen floating above the city.
Stunned pedestrians stopped in the middle of the street in awe, while others pulled out their mobile phones to record.
A one minute clip appears to show the anomaly turn round, while onlookers laugh nervously.
“It looks really like a bell”
It was uploaded to YouTube by Amirreza Milad, who claimed it was “huge like a building”.
But the footage was soon picked up by popular conspiracy channel secureteam10 and had racked up more than 100,000 hits in a matter of hours.
And Tyler Glockner, who runs the page, speculated it could be secret Nazi technology.
“It looks really like a bell specifically out of Germany in the 1940s,” he said.
“Germany was the very first nation to get hold of reverse-engineered alien technology.
“Hitler harnessed the anti-gravity technology, which was then used throughout and after the war.”
Die Glocke was speculated to be a top-secret Nazi scientific device and secret weapon.
It was popularised by military journalist and author Nick Cook and others who associate it with Nazi occultism and antigravity or free energy research.
The “Wunderwaffen”, or “miracle weapon”, was allegedly created by Third Reich scientists working for the SS at a German facility known as Der Riese.
It is described as being a device “made out of a hard, heavy metal” approximately 2.7 metres (9 ft) wide and 3.7 to 4.6 metres (12 to 15 ft) high, having a shape similar to that of a large bell.