“We should just tear it all down,” one of the artists said jokingly, gesticulating towards the golden arches of a nearby McDonald’s. The lock on the third billboard had rusted and wouldn’t open, but they got into the base and turned off the illuminating lights. Sometimes they just take ads down, but if their actions prevent people from seeing outdoor ads, they think “it’s worth it.”

For the past six years, this collective of neo-situationist urban street artists have been creating and installing guerrilla protest advertisements across Europe. Sometimes the designs of “Brandalists,” as the group calls itself, are based on corporate advertising campaigns, with the key messaging and slogans subverted to reveal an anti-capitalist, anti-corporate message. Comprised of hundreds of street artists and backed by a loyal contingent of activists, it’s common to see their work dotted around major cities in Europe.

Drawing attention to issues such as climate change, corporate greed, and corruption, they have taken aim at high-profile brands like Nike, VW, Air France, Mobil, and Shell. One campaign linked Nike’s high-priced sportswear to knife crime, swapping the “i” in the Nike branding for a blade and depicting blood running from the trademark swoop. Another was in response to a Shell PR campaign trying to talk up the company’s attempts to address the burning of fossil fuels. The reappropriated message explicitly stated the ways in which the company was continuing to contribute to the issue, and embossed the firm’s logo with flames.

Comprised of hundreds of street artists and backed by a loyal contingent of activists, it’s common to see Brandalists’ work dotted around major cities in Europe.

When London’s Metropolitan Police Service (the Met) placed ads looking for volunteers, a group of subvertisers calling themselves the “Special Patrol Group” replaced them with ads outing the force as a racist and violent institution. On Black Friday, they targeted fast fashion and overconsumption, highlighting the effects on the developing countries that have to deal with our waste. One of the installations, placed outside an electronics store in Manchester, England, was a photomontage of young people stuck in one of the biggest electronic waste landfills in Ghana, Africa. Globally, an estimated 15 million people make a living mining old laptops and phones for raw materials.

The work of the Brandalists has not gone unnoticed, and not just by the general public. They have provoked serious responses from the Met (who once bizarrely cordoned off the scene of one of their actions) as well as multinational corporations. In 2015, a legal paper advised brands on what to do if they were targeted by Brandalists, explaining how the group was using social media to highlight its work.

One activist claims he was recently challenged by workers from JCDecaux, the French multinational corporation that installs outdoor ads on billboards. “We do the work and you’re just taking it down,” the workers complained. The confrontation became heated, and the subvertisers retreated after claiming they were doing it for a college project. JCDecaux did not want to comment for this story.

But interactions can be more surprising. Bill Posters, a pseudonym for the co-founder of Brandalism, told me about a run-in one group of women artists recently had with another billboard worker. “He said, ‘Are you supposed to be doing this?’ The artists who were installing the work said, ‘of course.’ ‘Well, look, you’re not doing it properly.’ He gave them advice and another tool from his van. They had the uniform on, they had the keys. He was thinking that they must be legit. The women said that it was quite empowering for them to hold their ground, blag them, and say we have a right to do this.”