As the trial of 29 suspects accused of involvement in the Madrid train bombings gets under way, the BBC's Danny Wood, in Madrid, profiles what will be very public - and protracted - proceedings.
Security around the Madrid courthouse is tight
To get anywhere near Europe's biggest trial of alleged Islamic militants you have to pass an armoured vehicle sporting an ominous looking heavy weapon, a line of policemen, some with sub-machine guns, and a colourful variety of security vans overlooked by a noisy, circling police helicopter.
The Spanish authorities have gone big on security, but it has not stopped people from finding out what is going on inside the courthouse.
This is a very public, transparent and hi-tech trial.
Spaniards can watch the sessions live on television or over the internet and assess the evidence for themselves.
The indictments - all 100,000 pages of them - have been digitised and at a wave of his finger, the presiding and rather intimidating Judge Javier Gomez Bermudez moves them onto flat-screen television sets for all to see.
A separate room has been set aside for victims of the train bombings where - in the company of a psychologist - they can watch the proceedings unfold.
But some of the victims and their families are inside the actual courtroom, very near the accused, most of whom are sitting together inside a transparent glass box.
'You are a murderer'
This is the first time they have had the chance to see their alleged perpetrators in the flesh.
The explosions killed 191 people and injured about 1,800
Ruth Rogado's mother was killed on one of the trains. During the trial, she found herself sitting just metres from the key suspects.
During the first morning session Ruth moved towards the glass and shouted towards one of the accused: "You are a murderer".
That outburst was understandable but unusual. So far the court sessions have taken place in an atmosphere of rather strange calm. The victims and their relatives appear exhausted and emotionally drained by it all.
Many are hopeful that this trial will bring them some form of justice and help to clarify what happened on 11 March 2004.
There are 29 suspects on trial, including six men the prosecutors regard as key figures in the March 11 plot.
But not all of the alleged prime suspects are still alive. The authorities say that seven important figures in the bombings blew themselves up in a flat in the Madrid suburb of Leganes one month after the attacks.
Among them was Abdelmajid Fakhet, known as "the Tunisian" - the man Spanish authorities refer to as the ringleader of the bombings.
But in spite of that, this trial is the best opportunity yet to assess the evidence and take a long hard look at how, why and what happened on 11 March 2004.
Controversy over evidence
The later court sessions will directly involve victims and their special teams of lawyers.
Defendant Rabei Osman refused to answer prosecution questions
Maria Puente is the spokesperson for lawyers representing the families of 84 dead and 300 injured from the Association for Victims Affected by the 11 March Attacks.
She wasn't concerned that the first accused, Rabei Osman - and probably other defendants that follow - refused to answer questions from the prosecution.
"It's logical from the point of view of the defence because the more someone talks, the more they could incriminate themselves.
"But, from my point of view the fundamental thing about this trial is not the declarations of the accused, but all the witness statements, all the evidence gathered by the police, the DNA, fingerprints, the analysis of the explosives."
Three years after the attacks, there is still a lot of controversy over the evidence.
Unlike the attacks on London and New York, in some ways, the Madrid's bombings divided rather united the people.
General elections came three days after the bombs. Many Spaniards directly linked the bombings to Spain's support of the war in Iraq.
That, combined with the way the Popular Party was perceived to be deliberately misleading the people by insisting that ETA was the culprit, are thought to be vital reasons behind their election loss.
To this day, the Popular Party continues to insist that ETA could have been involved in the attacks.
Presiding judge Javier Gomez Bermudez has digital technology at his fingertips
Gustavo de Aristegui, a Popular Party spokesperson says the local cell of Islamic militants blamed by the authorities for Spain's worst ever peace-time bombing, could not have carried out such a well planned attack by themselves.
But according to the judicial investigation into the attacks - and the Spanish and European intelligence services, there is no evidence to suggest an ETA link.
Angel Salgado was on one of the trains that exploded and says the allegation by some sections of the media and the conservative Popular Party of a possible ETA link is just political games.
But one survey show that about 30% of Spaniards still think it is possible ETA had something to do with the attacks.
That contradicts the findings of a Spanish judge.
This trial is the result of a two-year investigation by Judge Juan del Olmo.
In April 2006 he concluded that the bomb attacks were the work of a local cell of Islamic militants with links to the Moroccan Islamic Combatant Group and inspired, rather than directed by, al-Qaeda.
Del Olmo said Spain's support of the war in Iraq encouraged these alleged militants to carry out their attack.
He also found was no evidence suggesting an ETA link in the bombings and for that reason, stopped investigating that possibility.
'Justice must be done'
But ironically, calling off the ETA line of inquiry, has only made the doubters think there could be something to hide.
What appear to be police mistakes - that many experts explain as errors made during the chaos of the immediate bombing aftermath - have also contributed to what many Spaniards see as conspiracy theories surrounding the bombings.
A backpack that was recovered with unexploded bombs appears to have temporarily gone missing.
According to sections of the Spanish media, some police reports say the explosives used in the attacks contained the same substance as bombs used by ETA.
That was discounted by the judicial investigation. But the doubters continue to doubt.
Jose Maria, an old man who lost a close family member in the bombings, only wants one thing: "I don't know if justice will be done but that's all I ask for."