Thirty years ago, a rapt world watched the unfolding of one of the great city stories of all time. Every hammer blow chipping away the imposing grey blocks of the Berlin Wall, which had come to embody global geopolitical divisions, seemed to herald a more united future.

Since then, however, our world has fractured anew and our cities feel more divided than ever. When the Berlin Wall fell, there were two border walls in Europe; now there are 15. Nor is this fracture merely physical: many cities are havens of wealth and privilege for those who hold the access codes, hives of struggle and poverty for those who do not. Wherever I travel to report I have always been struck by how different people can have such contrasting experiences of the same city – and it’s no different at home, in my neighbourhood of Camberwell, south London, where upscale coffee shops and gang violence occupy the same stretches of road.

When we started Guardian Cities in 2014, many of the stories we reported, on topics such as gentrification and car use, were ultimately about division and inequality – and that was before the votes for Donald Trump and for Brexit upended the US and UK, the war in Syria sparked an unprecedented migration crisis, and climate change finally seized the imagination of those who realised that it was likely to be the poor who suffered most.

Divided Cities is the result of that reckoning – a new global documentary series of five stories, from five cities around the world, that reflect these major faultlines in surprising and troubling ways.

Over the last 12 months our team – Guardian executive producer Jess Gormley, producer Anetta Jones, film-maker Max Duncan and myself – worked with our contacts around the world to identify what we believe to be some of the more vital and startling ways cities are divided today. All we knew at first was that we wanted to move beyond Trump and Brexit – both of which have sucked up so much oxygen that many equally important stories are going unreported – and to rethink division from a fresh perspective.

Facebook Twitter Pinterest Migrants sit atop a border fence during an attempt to cross from Morocco into the Spanish exclave of Melilla. Photograph: José Palazón/Reuters

That meant avoiding some quite well-covered cities: the “peace walls” of Belfast, for example, or the famously divided city of Jerusalem, a place as thick with history as it is with journalists. It also meant moving on from certain well-trodden urban inequalities such as gentrification or the conflict between cyclists and drivers, which, though emotive flashpoints, are issues we have covered (and will continue to cover) in dozens of different ways.

Instead, the stories that jumped out to us came from five continents and embodied five entirely different conceptions of what it means to be a “divided city”. We started in Nicosia with a classic of the genre, as it were: the UN-patrolled barricade that cleaves the island of Cyprus into a mostly Greek Cypriot south and Turkish Cypriot north. The story that seized us most strongly there, however, was new: a young generation who didn’t experience the war, and who reject the military conscription that requires them to point guns at their friends across what is now an shabby, overgrown buffer zone.

In Africa, meanwhile, we were fortunate enough to be present on the ground for one the most dramatic, dangerous and daring events in the world’s ongoing migration crisis: a night-time climb of the border fence at Melilla. Along with Ceuta, Melilla is a truly unusual city – a Spanish outpost in north Africa, separated from Morocco by a fence. Hundreds of people, mostly from sub-Saharan Africa, end their treacherous journeys across the desert by hiding out in forest camps near the fence, waiting for the right moment – sometimes as long as six months – to try to climb en masse in the dead of night. In May this year, one attempt saw almost 60 migrants make it over. They stepped on to EU soil, claiming asylum. But the far-right political party Vox wants them out, and is proposing two ideas that will sound troublingly familiar: to “make Spain great again” by building, you guessed it, a wall. It’s a closed-door attitude that makes no provision for another quirk of this fascinating city: 30,000 people cross through the fence daily for work, but who must return to Morocco each night. Many work as “porters”, exploiting a legal grey area that allows them to carry goods tax-free. The trade is tolerated by the authorities, and the economic benefits it brings are relied on by both Melillans and Moroccans.

Play Video ‘Make Spain great again’: does Melilla really need a Trump-style wall? – video

Other cities lack physical barriers entirely, but are no less split. The socialist capital of Havana boasts a truly bizarre system of two currencies: one for the socialist state sector, which pays the salaries of doctors and other civil servants; and one for the newly booming private sector, which is pegged to the US dollar and is worth 24 times the state currency. This oddity leads to some obscene ironies, such as doctors earning so little that they can’t afford to feed their own families, leading some to abandon their training and communities and take up unrelated private sector roles, such as driving taxis for tourists.

The very wealth of the United States to the north, meanwhile, generates equally perverse schisms. One of the worst of the country’s so-called “food deserts” is in Memphis, Tennessee, where many neighbourhoods lack what seems a basic right in richer neighbourhoods – a supermarket. For poorer residents, most of whom don’t own cars, that either means long journeys on multiple buses, or feeding your kids junk from fast-food restaurants and convenience stores, where much of what is sold as food doesn’t truly qualify for the name.

Finally, if there is one unfolding phenomenon that unites us all in division, so to speak, it is the environmental crisis, rapidly shaping up to be the greatest inequality issue we are likely to face as a species. As India’s capital, Delhi, grows dark under a cloud of smog that refuses to dissipate, following a summer where more than a hundred Delhi residents died as a direct result of overheating, we found a city riven by “climate apartheid”. Some can afford to protect themselves from the elements (via cars, air purifiers, and air conditioned spaces). Others must live, work, suffer and sometimes die in the heat and pollution.

None of these divisions is carved in stone. In each city, we found irrepressible people who don’t just passively accept their fate. The young Nicosians willing to face prison rather than take up arms against other teenagers on the opposite side of the divide. The migrants to Melilla who lift each other to better lives, and the Spanish citizens who help them to keep Spain a welcoming country. The Cuban doctors who celebrate the successes of socialism yet bravely speak out against the warping effects of the two currencies. The Memphians who try, and fail, and try again to get fresh, nutritious food to their neighbourhoods so that McDonald’s and CVS aren’t the only places to get a meal.

After five years of Guardian Cities, we wanted to ask a question that has hummed behind most of the work we’ve done: is division inevitable? We hope you watch the series and share your own thoughts, either on Twitter (@chrismichaelgdn or @guardiancities), Facebook, Instagram using the hashtag #guardiandividedcities or on YouTube.

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