The airport has long been the subject of wild theories. Now it’s getting in on the act with jokes about its new project

If you pass through the great hall of Denver airport in Colorado this weekend, you won’t fail to notice the huge amount of building work going on there. Or at least … it looks like building work.

Large posters, placed on hoardings around the terminal, cast doubt on what’s really going on. One reads: “Construction? Or cover up?” and features Illuminati insignia on a yellow hard hat. Another shows a reptile head poking out of a suit and asks: “What are we doing?” It offers three potential answers, one of which is: “Remodelling the lizard people’s lair.”

Destiny. (@CoolAsPhuck) Denver International Airport is really trolling y’all conspiracy theorist with their new construction signs 😂 pic.twitter.com/Gg29dURhHN

The posters seem like some of the wackier outbursts of conspiracy theorist and Trump fanatic Alex Jones, hinting that the airport is part of some kind of satanic plot. In fact, they’ve been put there by the airport as part of a new advertising campaign, which plays up the fact that ever since it was opened in its current iteration in 1995, Denver international airport (DIA) has, for some reason, been the subject of conspiracy theories.

Facebook Twitter Pinterest A photo of the dedication stone at Denver international airport, featured in an exhibition about conspiracy theories related to the airport. Photograph: Denver International Airport

There is, to give the tinfoil hat crowd their due, lots that is fishy about DIA. The dedication stone, created for the airport’s opening, bears the logo of the Freemasons and was paid for by two Freemason grand lodges in Colorado, as well as something called the “New World Airport Commission”, an organisation about which there is almost no information. It has led conspiracy theorists to argue that their airport is the headquarters for a secretive new world order linked to the masons or the Illuminati.

Facebook Twitter Pinterest Mural by Leo Tanguma at Denver international airport. Photograph: Denver International Airport

There are also unusual murals in the airport, painted by the artist Leo Tanguma, which depict creepy images of manmade environmental destruction and genocide. They have been seized upon by conspiracy theorists, although they often neglect to mention that they are part of a four-part series, and the final two murals depict all of humanity coming together to live in harmony and peace.

Other theories that have been touted include suggestions that the runways were arranged in the shape of a swastika and that unusual markings on the airport floor are satanic symbols. Another is the huge bunkers under the airport, allegedly created for an automated luggage system that malfunctioned when the airport opened, are in fact an underground lair for the “lizard people”.

The theories have been passed around on conspiracy forums and YouTube for years, and were also the subject of an episode of Jesse Ventura’s Tru TV show Conspiracy Theory. In 2008, the airport got a new chief executive, Kim Day, who embraced the suspicion surrounding the airport. Day’s approach included an exhibition about the airport’s suspicious history, art exhibits that used Illuminati imagery, a conspiracy costume party and even a competition to win a trip underneath the airport, to examine its mysterious underground facilities.

Now the airport is at it again: with construction taking place in the great hall, they’re playing up suggestions that something unearthly is going on. As well as the posters, there’s also a new web page called Den Files which includes bonus conspiracy theories like “the date of the airport’s dedication is March 19, 1994. And if you add those numbers together (1+9+1+9+9+4), you get 33 ­– the highest level one can achieve in Freemasonry.”

Indeed, across YouTube, Google and social media, a majority of results in a search for Denver airport conspiracy theories contain content made by or in conjunction with the airport itself suggesting that while the conspiracy world may have moved on to other things, bosses are keen on the idea that there is more to DIA than being America’s fifth-busiest airport …