“If you can prove that Bielefeld really does not exist, you will win a million euros,” states the city's homepage in a section titled “#DieBielefeldmillion. Das Ende einer Verschwörung (The end of a conspiracy theory).”

The city, home to just over 330,000 people, has struggled for years with the perception that it doesn't actually exist, and is, in fact, all part of an enormous conspiracy. 

Now on the 25th anniversary of the theory, it aims to put the myth to bed (or hand over a €1 million).

“All friends of the Bielefeld conspiracy theory have a last chance to prove it!” tweeted Bielefeld on its official city account, with a picture proclaiming “Bielefeld: too nice not to be true!”

This belief stems from a series of postings on Usenet in 1994 by university student Achim Held, who wanted to demonstrate how quickly conspiracy theories can form and spread. 

He noted that you never seem to meet anyone from Bielefeld, nor do you ever hear of any major industry or German innovation originating in the town. 

Bielefeld, in past centuries, is believed to have had a reputation as a prosperous centre of the cloth trade, as well as being the headquarters of baking conglomerate Dr Oetker. Today it is also home of the University of Bielefeld, which has a student body of around 25,000.

Is this the campus of the University of Bielefeld or part of a complex cover-up? Photo: DPA

Held also posited that shadowy individuals, only known as 'SIE' ('THEM') must be responsible for the illusion of a 'Bielefeld', and work to keep the truth from the German people. 

Held's creation quickly spread from the internet into the real world, becoming a part of German popular culture, and making the city the butt of countless jokes by comedians. 

Even Chancellor Angela Merkel has referenced the conspiracy in a speech she gave, joking that although she had attended a meeting in Bielefeld in 2012, she has no way of knowing whether she was really there. 

Of course, such a warm-hearted, feel-good story of a internet joke gone viral could be the perfect cover story for a much darker truth. 

Over the last twenty-six years, thousands of internet postings have suggested that the alleged city is merely a front for groups as diverse as the Freemasons, extraterrestrials, the CIA and the German government, among others. 

Merkel in Bielefeld's City Hall in 2012 – or was she? Photo: DPA

The city referenced some of the conspiracy theories itself: “Bielefeld doesn't exist? Bielefeld should be the access to Atlantis? Little green men are supposed to have disguised their spaceship as Bielefeld University?” it wrote on its website.

Previous efforts to pierce the veil of secrecy and ascertain the truth of what Bielefeld truly hides have to date come to naught, with investigators unwilling or unable to provide compelling evidence. 

At the time of publication, The Local could not confirm whether the €1 million reward was a genuine push for publicity, trading on the joke's popularity, or merely another in a complex web of lies, meant to deceive us all.