Fifty kilometres north of Madrid, in the granite mountains of the Sierra de Guadarrama, is the tallest stone cross built anywhere in the world. More than 150 metres high, it stands guard over a vast basilica hewn into the rock below.

The sprawling architectural ensemble, coldly symmetrical and entirely grey, shows occasional traces of life. It is home to a Benedictine abbey, along with a religious boarding school and hospice. There is a decent restaurant that specialises in traditional Spanish fare, and a mud-covered football pitch that comes to life whenever the pupils emerge to play a match.

Mostly, however, this is a place of death. Known as the Valle de los Caídos, or Valley of the Fallen, it is the final resting place for more than 33,000 bodies. With one notable exception, all of them were killed during the Spanish civil war, which lasted from 1936 to 1939. The odd one out is the man who started the bloody slaughter, and emerged from it victorious. His grave can be found right behind the high altar, at the very end of the imposing, windowless basilica: a modest granite slab, perpetually adorned with a bouquet of fresh flowers and the simplest of inscriptions: Francisco Franco.

The Spanish dictator died four decades ago this year but his resting place, much like his legacy, is far from settled. Outside Spain, Franco is often situated alongside Hitler and Mussolini as one of the continent’s most reviled fascist leaders, a brutal dictator who plunged his country into war and went on to preside over the death, incarceration, torture and exile of hundreds of thousands of his opponents.

In Spain, however, the government continues to pay for the upkeep of the Valle de los Caídos, tombstone and all, which forms part of the National Heritage. Hundreds of thousands come to visit the site every year. Spain’s Roman Catholic Church, meanwhile, jealously guards its role as the custodian of the Valley, and provides the monks and priests who sanctify the vast granite complex with their daily songs and prayers.

Even 40 years after Franco’s death, there is no national consensus on what the civil war and his dictatorship mean. Only a tiny minority voice genuine nostalgia for the old regime but the number of those clamouring for a frank reassessment of the past — and for expelling Franco from his privileged tomb — is not large either. As a topic of conversation, the former dictator and his deeds are widely shunned, whether in school, in parliament or around the family table. Polls are few and far between but those that are taken regularly show a lingering sense of ambivalence, perhaps linked to the extraordinary economic boom that occurred under the later years of the Franco regime. One typical survey found that six out of 10 Spaniards believe that Francoism had “both good sides and bad sides”.

Celebrating the anniversary of Franco’s death at his tomb in the basilica of the Valley of the Fallen

But it is not just in the Valley that Franco continues to have his place. Despite a purge during the past decade, many Spanish cities still boast streets and plazas that honour his memory. Even the odd statue has survived. There is a prominent foundation dedicated to celebrating the dictator’s life and work. Once a year its members and other Franco sympathisers come to the Valle de los Caídos for a special mass, and to pray for his eternal soul.

To some Spaniards, the site — and the annual ritual — is an abomination, a stain on the country’s democratic record. They argue that Spain, perhaps uniquely in western Europe, has never made an effort to openly confront its past. Far from allowing old wounds to heal, this failure has, in fact, kept old divisions alive for longer than anyone thought possible — the original sin of Spanish democracy, still unatoned after all these years.

One man who believes this more strongly than most is Emilio Silva, a burly political scientist and journalist who rose to prominence over the past decade as the co-founder of Spain’s historical memory movement. “Can you imagine a church in Germany where the priest prays for the soul of Hitler? Can you imagine a square in Italy that is named after Mussolini?,” asks Silva, over coffee in a noisy bar in Madrid.

The movement he started some 15 years ago is best known for locating and digging up the graves of Spanish Republicans killed by Franco’s Nationalists. More than 1,300 bodies have been recovered from roadside ditches and secluded forests, and accorded a proper burial. For the relatives, the process has often been momentous — allowing them finally to come to terms with six decades of pain and grief.

The basilica is part of the 'Fallen' complex near Madrid conceived by Franco

The broader aim of Silva and his allies, however, is to shatter Spain’s so-called pact of forgetting — the unspoken agreement between left and right in the wake of Franco’s death to look to the future, not the past. In legal terms, that pact is cemented in the 1977 amnesty law, which shields former Franco officials — including the regime’s most notorious torturers — from criminal prosecution. Yet it is also reflected in Spain’s schools, where the history of the civil war and Franco’s dictatorship remain marginal subjects. And it finds an echo in the singular absence of any national museum or monument (aside from the Valley) to commemorate the war. “We are a country full of ignorance,” says Silva. “If there wasn’t so much ignorance, Franco would no longer be there [in the basilica]. For a society with even a little bit of understanding, it would simply be intolerable.”

To its defenders, the Valle de los Caídos is, above all else, a site of mourning and reconciliation. They point out that the mass tombs that line those heavy granite walls hold the dead of both sides. But they often fail to mention that the Republican dead were brought to the mausoleum without consulting their families (and that they are held in some cases against the express wishes of relatives). Neither do they question why any Republican would wish to lie buried in a tomb so laden with Francoist and fascist imagery.

At least once a year, the notion of reconciliation becomes impossible to maintain: on November 20, the anniversary of Franco’s death, his supporters arrive from all over the country (and beyond) for a special mass.

I have rarely had cause to attend Catholic mass during my life but even regular worshippers are likely to leave this particular ceremony in a state of dazed wonderment. Part of this has to do with sheer sense of drama.

Emilio Silva, co-founder of the Association for the Recovery of Historical Memory, visits a Republican grave at Colmenar Viejo cemetery, north of Madrid

At the precise moment of the transubstantiation, when the bread and wine are symbolically converted into the body and blood of Christ, the vast underground basilica is plunged into darkness. An invisible helper turns off all lights save for a single spot that is directed at the body of Christ on the cross, along with the hands of the priest holding aloft the wafer.

The priest, who is also the abbot of the Valley’s Benedictine monastery, then starts his homily with a prayer for the soul of Francisco Franco and José Antonio Primo de Rivera, the founder of Spain’s fascist Falange movement. Both men died on November 20 but they are separated by a political eternity: Franco passed away in his bed, peacefully, after 36 years of unopposed rule. Primo de Rivera was killed by a Republican firing squad in 1936, just months after the start of Spain’s civil war.

The two bodies occupy pride of place in the gloomy basilica, buried in front and behind the altar. Standing at the lectern just above, the priest praises the two fascist leaders for their decision to “forgive their enemies and seek their forgiveness for themselves”.

I was told that some worshippers are likely to make a fascist salute but I had not expected arms to be raised quite so brazenly. Some make a discreet, hasty salute on their way to receive Holy Communion; but all inhibitions melt away once the priests, monks and choirboys leave the church. Franco’s grave is quickly surrounded by dozens of admirers. They lay down red flowers and kneel to touch the rough, grey stone. Some offer a personal prayer. Dozens straighten their back and offer the raised-arm salute, while friends and wives snap pictures. Shouts of “Viva Franco!” and “Viva España!” ring out through the vast basilica. Neither the guards from Spain’s National Heritage nor the remaining monk try to intervene.

Standing quietly is Jaime Alonso, the vice-president of the Francisco Franco Foundation and the public face of hardcore Francoists in Spain today. He whispers a prayer and crosses himself but then quickly turns away from the more raucous crowd surrounding the dictator’s grave. Impeccably dressed and softly-spoken, Alonso is a lawyer by profession and Francoist by passion. Armed with a wealth of numbers, dates and facts, he makes a resolute case for Franco’s defence when I catch up with him back in Madrid.

He tells me he grew up with a vision of Franco as the “father of the nation”, and views him still as “the man of providence who came to save Spain”. Selfless, upright, a brilliant military commander and great political strategist, Franco is hailed as a towering figure in Spanish history, comparable only to the medieval rulers who drove the Moors from Spain in 1492 or the great kings who held sway over an empire stretching from Peru to the Philippines.

Jaime Alonso, Vice-president of the Francisco Franco Foundation

Alonso vigorously defends Franco’s military putsch against the country’s elected government in 1936, which marked the start of the civil war, as a necessary step to put an end to the chaos and violence of the period. “There was no other option. They could either fight or let themselves be killed,” he insists.

The foundation is located in a third-floor apartment just up the road from Real Madrid’s imposing Bernabéu stadium. The offices are packed with memorabilia, signed photos, oil portraits, thousands of books and an archive. There is even a small souvenir shop, where visitors can pick up a Franco ashtray for €4.50.

For all his enthusiasm, Alonso admits that there are few genuine Francoists in Spain today. Since the return of parliamentary democracy to Spain, there has only been one openly Francoist member of parliament. Even during the recent economic crisis, with millions of Spaniards desperately searching for work, there was no sign of revival in Francoist sentiment.

Yet Alonso is convinced that Franco lives on. Why else, he asks, would the country’s political mainstream be so silent about his rule? “They are afraid of him. They know very well that Franco is more than just a reference, that he is something embedded in the culture of the Spanish people as a solution. Today, even if everything falls apart, we have a national ideal that stays with us and that is passed on in our genes. How can Francoism revive today? As bad as the situation is, the idea is there.”

What is striking is not so much the historical narrative put forward by the Franco Foundation but the absence of any official challenge to it. I have asked dozens of Spaniards what they were taught about the civil war in school. The answer is, almost invariably, nothing. Spain’s parties have never been able to agree on a joint condemnation of the Franco dictatorship, or an official apology to its victims. There has been no official commission and no national museum offering a unified narrative. Even 40 years after the death of Franco, it seems Spaniards find it impossible to reach common ground about their recent history.

For Javier Cercas, the Spanish novelist and writer, the interplay of memory and history, and the stories and lies people tell themselves about the past, have long been a subject of fascination. His 2001 book Soldiers of Salamis is widely hailed as one of the great novels about the civil war. I call him up a few weeks after the release of his latest book, The Imposter, which deals once again with history, war, terror — and the lies they bring forth. The book contains an entire chapter about Spain’s own struggle — and ultimate failure — to come to terms with its history.

Javier Cercas, author of 'Soldiers of Salamis', a celebrated novel about the civil war

“A country must have a basic accord about the past,” Cercas tells me. “Britain has it. Germany has it. All the strong democracies have this basic accord. But Spain hasn’t.” The reason for this, he argues, is obvious: “There was no rupture in Spain after Francoism. There was a transition, there was peaceful and progressive change from dictatorship to democracy. This means that the Spanish right did not break completely with Francoism. It would be wrong and absurd to say that the Spanish right is Francoist. It obviously isn’t. But it has never been able to bring itself to condemn Francoism.”

Not everyone is convinced that this matters. José María de Areilza, a professor of law at Esade business school and former government adviser, speaks for many when he argues that Spain was right to look to the future and “leave the past to the historians”.

“There is no one way to deal with the past,” he tells me. “Franco died in his bed. But everything that has happened in Spain since has condemned him. He is being condemned every day by the normal functioning of our democracy, by our constitution. Spain has moved on by doing, by acting.”

For Cercas, however, the country’s failure to openly confront the past leaves Spain in a state of heightened fragility. “If there is no accord over the past, then the past can always be used, can always be manipulated,” he says. “There is no accord over our past, and that means that finding an accord over our present and our future is much more difficult. Can we live with this? Yes, we can live with this. But would we live better if we had a common narrative? We would live much better.”

The closest that modern Spain ever came to challenging the pact of forgetting was under the Socialist government of José Luis Rodríguez Zapatero, the prime minister from 2004 to 2011. The Zapatero government provided generous funding to unearth Republican war graves, and passed a law calling for the removal of Franco statues and street names.

It faced bitter opposition from the centre-right Popular party, and from Spain’s Roman Catholic Church (which served as a pillar of the Franco regime). At the height of the controversy, the country’s conference of bishops published a searing attack on the government, saying it was “opening old wounds” and “threatening the tranquil co-existence”. The archbishop of Madrid put it even more bluntly. Sometimes, he remarked, “One has to know how to forget.”

Podemos, a new anti-establishment party supported by young Spaniards

Towards the end of its tenure, the Zapatero government finally decided to tackle the biggest totem of them all: the Valley of the Fallen. It appointed a commission of experts and asked it to draw up proposals for an overhaul of the site. The commission was formally established in May 2011 — just six months before a general election that Zapatero knew he would lose. Whatever conclusions its members would reach, they were almost certain to be filed away the very instant that the new centre-right government took over.

Francisco Ferrandiz knew he was part of an exercise in futility but decided to accept the invitation to join the commission all the same. A social anthropologist at Spain’s National Research Council, he had closely followed the work of the historical memory movement. Here was a chance to shape the debate over one of the most contentious monuments in the world today.

In the end, after much internal wrangling, the commission called for a radical overhaul: it suggested removing Franco’s grave from the basilica and burying him elsewhere, and transferring the body of Primo de Rivera from its privileged site to the mass graves that line the church. Just as importantly, they wanted to convert the sections of the site that house the dead into a national cemetery — and so remove it from the oversight of the monks.

As expected, the document was shelved immediately by the new government. Asked about the future of the Valle de los Caídos in 2013, the deputy prime minister fell back on the Popular party’s standard line that any change requires the “consensus” of all parties. That consensus remains as elusive as ever.

For all his frustration, Ferrandiz says he has not lost hope that a new generation of Spaniards will eventually demand a less circumspect relationship between the present and the past. He points out that Spain’s political order is now under scrutiny as never before. The transition itself has become almost a dirty word for a new generation of political activists who are desperate to sweep away what they see as a deeply corrupted system.

Franco is being condemned everyday by the functioning of democracy. Spain has moved on by acting

“We had the prestigious transition that is being taught all over the world as an example of how to move cleanly from a dictatorship to democracy. Now we find that this transition is under fire because it glossed over some of the thorniest issues of the dictatorship — and let the perpetrators die in bed without ever facing their responsibility. Now we have a new generation saying: ‘We have to face this.’”

That new generation is embodied by Podemos, an anti-establishment party founded only last year and now vying to become one of the largest parties in Spain. Some of its leaders are former activists in the historical memory movement — a background that helps explain the almost visceral rejection of what Podemos leaders refers to as the “transition regime”.

Younger Spaniards are less inclined to fear a return of political instability — or to regard Franco as a totemic issue that must not be raised. For many, the dictator has become a figure of ridicule. “Franco represents everything I don’t like about Spain and about Spanish history — the ultra-right, the relationship between church and state and the whole communion-and-daily-mass way of life,” says Sagrario Monedero, a 33-year-old political activist who works for a women’s rights organisation in Madrid. “But he is also a bit of a comical figure — this small man with a pot belly and a high-pitched voice,” she adds.

Like a growing number of young Spaniards, Monedero has never visited the Valley of the Fallen. She regards the monument as an outrage but also suggests that her generation sees no urgent need to tackle the Franco legacy. “History has already given its verdict.”

It is an argument that goes a long way towards explaining the indifference about Franco in Spain today. But if history has, indeed, made its verdict, why is it not being executed? Why is it so hard for Spanish democracy to touch that brooding mausoleum in the mountains?

“Let’s take this terrible monument as an opportunity,” says Ferrandiz. “It is the biggest Francoist monument of them all, and it is where all the complexities come together. If the debate has to happen somewhere, if we are to find a consensus about our history, it has to be around the Valley.”

Wandering amid the acres of grey granite, it is not easy to share Ferrandiz’s hope that change is in the air. All that heavy stone and polished bronze convey an aura of timeless permanence. Who will have the strength to push aside the massive slab of stone that covers Franco’s grave? What ghosts will awake the day that Spain starts looking unflinchingly into the past, and attempts to finally separate perpetrators from victims?

No one knows. Perhaps the only certainty is contained in the famous line from William Faulkner cited in Cercas’s latest novel, one that could serve as the summary of Spain’s ever-simmering history wars: “The past is never dead. It’s not even past.”

Tobias Buck is the FT’s Madrid bureau chief

Franco’s life

1892 Francisco Paulino Hermenegildo Teódulo Franco Bahamonde was born on December 4 in Ferrol, a provincial port in northwest Spain.

1907 Like several generations of family before him, he seemed destined for a career in the navy but, instead, joined the Military Academy at Toledo. He graduated as a lieutenant three years later.

1917 He was made the youngest major in the Spanish army after a campaign in Morocco, during which he was severely wounded by a gunshot to his stomach. It is said he would have died if he hadn’t been inhaling when the bullet struck, as this saved his intestines from being hit.

1923 Franco, now leader of the Spanish Legion, married Carmen Polo. They had one daughter, María del Carmen, born in 1926.

1926 He was promoted to the rank of brigadier-general. Reputedly, this made him the youngest general in Europe since Napoleon.

1936 In July, civil war broke out in Spain between the leftwing Republicans and the rightwing Nationalists, led by General Franco.

1939 The last Republican forces surrendered in April. Franco declared himself “generalissimo”, head of both state and government.

1939 The second world war began in Europe in September. Franco’s Spain remained officially “neutral” throughout the conflict, even though he had previously received help from Hitler and Mussolini during the Spanish civil war.

1947 Franco reinstated the monarchy but with himself as de facto regent for life.

1950s Spain was brought in from the cold and admitted into the United Nations, and was visited by US President Dwight Eisenhower.

1960s and early 1970s The country enjoyed an economic “Spanish Miracle”, and tourism flourished.

1975 On November 20, Franco died of natural causes. He was buried at Valle de los Caídos.

Research by Spencer Brown

Photographs: Alfredo Caliz; Getty; Panos Pictures