Walking through Barcelona it's easy to forget that great political passions were once played out in the streets. Take a tour of Spanish civil war sites with Stephen Burgen

It is hard to imagine, standing at the top of La Rambla, in the multicoloured swirl of half-dressed tourists, Mexican hats and Gaudí paraphernalia, that it was here in Barcelona on 19 July 1936 that the opening shots were fired in what was to become the Spanish civil war. Harder still to picture the anarchists of the CNT (Confederación Nacional del Trabajo) union running a city that is now firmly under the thumb of dour Catalan nationalists, or to believe that what is soon to be a gigantic Apple store was once the Communist party HQ and was draped with vast portraits of Lenin and Stalin.

From that summer's day until it fell to Franco's forces on 26 January 1939, the city lived through the entire gamut of revolution, from the heady days of hope and people power through infighting, betrayal, aerial bombardment and eventual, crushing defeat. It was Barcelona's revolutionary fervour that, more than anything else, helped to inspire volunteers from across Europe and the Americas to join the International Brigades and fight for the Republican cause.

Curious, then, in a city that boasts 50 museums – among them museums dedicated variously to shoes, cannabis and erotica – that there is not one that commemorates either the triumphs or the sufferings of the civil war. This act of remembrance has been left to an Englishman, Nick Lloyd, who has been running a tour of the key sites and events of civil-war Barcelona for the past two and half years. The tours are in English and Spanish, and each lasts from two to three hours.

"The people who take the tour come from all over the world. If there's a common link, it's Orwell and anarchism. There are a lot more anarchists out there than you'd imagine," he says.

Nick, who hails from Stockport and makes a modest living from a combination of the tours and teaching, says the idea came from digging into the working-class history of the city he has called home for the past 22 years.

"I felt uncomfortable at first because it's a cliché – the Englishman talking about the civil war," he says. "I spent a long time debating whether to do the tours with Spanish people, but my Spanish friends told me not to be so stupid. Plus, I've lived here for 22 years, so when do you stop being foreign?"

I join the tour on a Friday evening along with 12 members of a local theatre company who are researching a play. Most of them are Spanish and they admit that they learned very little about the civil war at school. "Mostly just a list of dates," says one. "Your own history is the one you know least about," says another, who tells me later that the war was never discussed at home.

"It is a suffocating, hot day," Nick says as he begins to describe the events of 19 July. We are gathered on the south-east corner of Plaça Catalunya on what is also a suffocating, hot evening in July. Using the present tense is one of the ways in which Nick manages to conjure up a vision of a Barcelona wholly different from the city that fell in love with itself during the 1992 Olympics, before which it was a grey town divided between the poor in the old city and the rich up on the hill in Tibidabo.

He is describing the events of day one, at the hopeful start of the uprising. An English hen party in matching pink shrieks past as he describes the gun battles with the police and the column of CNT workers storming the barracks and seizing 30,000 weapons. He talks about the Olimpiada Popular organised in protest against the Olympic Games in Nazi Berlin. The alternative "Popular Olympics" attracted 6,000 athletes from 22 countries and were scheduled to open on the day that the uprising began.

"Imagine, the city was full of foreigners witnessing this revolution," Nick says. "About 300 stayed to fight and they were some of the first foreign volunteers, long before the International Brigades."

We move down La Rambla to the Hotel Continental, Orwell's elegant base in the city. Nearby a crowd gathers around a group of trileros (three-card conmen), one of La Rambla's modern hazards. Nick gets one of the actors to read a passage from Homage to Catalonia in Spanish. "Waiters looked you in the face and treated you as an equal," Orwell wrote. "Servile and even ceremonial forms of speech had temporarily disappeared. Tipping had been forbidden; almost my first experience was receiving a lecture from a hotel manager for trying to tip a lift-boy."

Nick plays a revolutionary song on his iPad and the tour continues. I ask one of the Spaniards if she finds it strange, getting this history lesson from a Brit. "Not at all," she says. "Everyone knows that the English know more about the war than we do."

Plaça Sant Felip Neri, with shrapnel scars in the church wall.

This is partly thanks to writers such as Orwell and Laurie Lee, who fought in the civil war, along with some 2,000 Britons who served as volunteers in the International Brigades. Furthermore, until Franco's death in 1975, the only impartial accounts of the war were written by British historians.

Outside the church of Santa Maria del Pi Nick tells us that 7,000 clergy were killed by the rebels. He shows us photographs of desecrated tombs of saints and militiamen posing beside mummified relics. He doesn't romanticise the struggle or the violence. In the Plaça Sant Felip Neri he points to the pockmarked walls of the church and says that after the war the fascists spread the myth that these were the bullet holes that marked where the rebels shot priests. The truth is they are the shrapnel scars from two bombs dropped on the square by the Italian air force, killing 42 people, most of them children in a nursery school. We are now two hours into the tour, and shiny, commercial Barcelona is disappearing behind a vision of a dark and increasingly desperate place.

We return to La Rambla and the Hotel Rivoli, formerly the headquarters of the Marxist POUM party that Orwell joined. Nick explains as best he can the complex political divisions on the Republican side that led to the "May Events" in 1937, when pro-Stalinist and other forces killed hundreds of anarchists and their supporters in three days of internecine struggle, an event that profoundly shaped Orwell's views on totalitarianism and also marked the death of the Rosa de Foc, the fiery rose, as anarchist-run Barcelona was known.

The last stop of the tour is the Bar Llibertària, a co-op owned by CNT members in Raval whose walls are a celebration of Catalan anarchism, with original posters and photos as well as newspaper clippings from the Spanish civil war. Sergio, who runs the bar, insists that anarchism has never gone away. He says that Catalunya's particular brand of libertarian anarchism is alive and well in the indignado movement that has risen up in the past year, especially in Barcelona, in response to unemployment, corruption and growing social inequality.

"What happened in Barcelona in 1936 was completely different from what happened in the rest of Spain," Sergio says. "Catalans talk about the fet diferencial, the thing that makes them different from the Spanish. But it's not botifarra sausages or the Catalan language that sets them apart – it's anarchism. That's the real difference."

Essentials



Spanish Civil War Tours by appointment and every Saturday 10am-1pm. The tour lasts three hours and is for groups of between 3-8. Price €20 per person. For more information, go to iberianature.com

• This article was amended on 23 July. Due to an editing error, the original article wrongly said that the rich of Barcleona lived on the hill of Montjuïc. It should have said Tibidabo.