"I wasn't even there for the worst of it," he said. "But I saw bombs fall, and I was told about how they bombed the Gran Vía, leaving the street littered with body parts, which also hung from the trees."
In 1938 Savoia bombers from Benito Mussolini's Italian air force rained bombs on the Spanish city as they broke non-intervention treaties to support General Francisco Franco's rightwing rebels in the Spanish civil war. The use of attacks from the air was designed to provoke panic, kill civilians and destroy morale. Within a few years, the technique would spread through war-torn Europe as cities such as Coventry, Hamburg and Dresden were subjected to blanket bombing.
Now, 75 years after one of those bombs killed his father, José, as he tended a vegetable plot near Barcelona's port, Cánovas has helped persuade a Spanish court to investigate Mussolini's air force for war crimes. The case was accepted by a Barcelona court last week. "These indiscriminate bombardments of civilians targeted densely populated neighbourhoods," a panel of three magistrates said. "The frontline was far away, making this a laboratory for future civilian bombardments and producing mass crimes that would be punishable by any law at any time or place."
Any remaining Italian expeditionary air force pilots and officers are likely to be dead or close to it, but Cánovas wants the truth to come out. And he wants Italy to publicly recognise its role.
"This is not about revenge," he said. "I have been a pacifist since I was 12 years old and I do not want to restart old arguments. I can pardon, but what we can't do is forget. It is important that people know the truth about what those particular Italians did at that time."
Cánovas's father was killed early in 1938, when Italian bomber squadrons based on the island of Mallorca began to ratchet up their bombing campaign. Mussolini sent instructions: "Start violent action on Barcelona tonight, with constant hammering diluted over time." Every three hours for the next three days a fresh wave of bombers appeared. Their bombs killed 670 people in attacks that appalled foreign onlookers and brought protests from the Vatican and the United States.
Even Franco accused Mussolini of wanting to prove that Italians could "horrify the world with their aggressiveness rather than charming it by their skill at playing the guitar". Mussolini ordered the campaign to be slowed down.
Since the second world war, Italians have seen former Nazi officials pursued in their courts for war crimes, but have rarely debated Italy's role in the Spanish civil war, when Mussolini deployed 60,000 soldiers and 750 aircraft.
But although Mussolini's troops allegedly also committed atrocities during campaigns in Libya and Ethiopia, and later in Slovenia and Greece, only one public apology has ever been given. In 2011 Silvio Berlusconi apologised to his friend in Libya, Colonel Muammar Gaddafi, and offered compensation.
While Cánovas has added his name to the private prosecution, the real organisers are a group of mainly leftwing Italians living in Barcelona.
One of these, maths teacher Guido Ramellini, said that the raids were among the first experiments in the bombardment of cities. "When the British wanted to know how to build bomb shelters during the Blitz, they called on expertise from Barcelona. I know some people will call us traitors to our homeland. But we believe all humanity is our homeland, and Europe too. There is no reason why we should bury the ghosts of Europe's past."
Ramellini and other members of the Altra Italia group in Barcelona have been trying to wring an apology out of Italy for years, but found it impossible while Berlusconi was in power.
In 1997, the former German president Roman Herzog formally apologised for the bombardment of the Basque town of Guernica. The atrocity, which inspired one of Pablo Picasso's most famous paintings, was carried out by the Luftwaffe's Condor Legion (with the help of Italian aircraft) as Hitler also threw his weight behind Franco. Britain has also never apologised for the carpet bombing of Dresden in the final months of the second world war.
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