If the walls of Abu Slim prison could speak, they would tell the horrific tale of two days in 1996 when Moammar Gaddafi's forces gunned down 1,200 inmates.
Those who lived still tremble with the memories of June 28 and 29. The families of those who didn't, who received terse death certificates only 12 years later, continue to be consumed with suffering.
But a three-day exhibition in the gutted grey complex in Tajura, east of Tripoli, invites Libyans to take a deep, hard look at one of the darkest moments of their history, pay tribute to the dead and demand justice.
The target of those demands is Abdullah Senussi, spymaster for the late dictator, whose empty promises to striking prisoners set the stage for the massacre.
Abdesalam Al-Ugbi, a 40-year-old sports teacher who lost his brother, insists that Senussi, now being held in neighbouring Mauritania, be tried in Libya and punished in accordance with the teachings of the Koran.
"We want him to get the death penalty, with the sword, the Islamic way."
It all started when prisoners reportedly overpowered and captured two guards, stripping them of their keys.
Their demands were simple: no more torture, trials, time in the sun, family visits, access to books and information about the outside world, and the punishment of abusive guards.
Abu Slim was a top security prison notorious for torture and human rights abuses during the time of Gaddafi, who ruled with an iron-fist for 42 years until a popular uprising led to his ouster and killing in 2011.
Ali Al-Kermi entered Abu Slim when he was just 22 and didn't leave for 28 years. He was arrested in 1984 for belonging to Liberation, an underground movement dedicated to creating an Islamic state in Libya.
In fluent French, he recalls the agony endured by prisoners. Electroshock, rubbing salt on razor cuts, ripping out nails and teeth, hanging prisoners on a rod like a "roasted chicken," beating the soles of the feet and and penetration with white-hot metal rods.
Now a father of four, the youngest of whom is only 39 days old, he heads an association for prisoners of conscience.
Kermi said he was in a different wing of the prison the day hundreds were shot dead. He remembers hearing the terrifying racket of bullets raining from soldiers on the rooftop.
How it all started has become part of the collective memory.
As the story goes, Senussi came to speak with the prisoners. He negotiated the release of the captive guards and promised there would be no reprisals.
Sheikh Mohammed Abu Sedra said he told Senussi the prisoners wanted "either to live as honourable people or die as martyrs. You are trying to kill us your way; we want to die our way."
He told AFP Senussi approved most of the demands as reasonable but said any trial of prison guards would have to be sanctioned by Gaddafi.
"We asked people to please get back in (to their cells) because they told us we would be safe," said Abu Sedra, who spent 21 years in Abu Slim, adding that he survived "only by the grace of God."
But many of the prisoners saw it coming, hugging each other and begging each other for forgiveness in what proved to be their final moments.
United in grief and the desire to see the perpetrators tried, entire families drift as in a dream through damp corridors and into tiny, sombre cells that were once packed tight with more than 20 men each.
Only in his forties, but already an old man, Khaled is agitated as he brings his new wife to his old cell and shares the details of his most troubled days: "See these holes? It was the only to way to speak to our friends. There was no electricity."
He says he was jailed for wearing a long beard and calling for an Islamic state during a "tyrannical regime that manipulated and distorted the Muslim faith to oppress its people."
Sumaya Mohammed, who lost four siblings in the massacre, said she "wanted to see the place where my brothers were tortured and kept in solitary confinement."
The bodies of those killed in the massacre were never recovered by their families, and Hafiz Rahayib simply wanted to know: "Where is my brother's grave?"
Children carry pictures of loved ones never met but still remembered.
The heart of the exhibition is a courtyard displaying handicrafts made by the prisoners -- such as pouches made of wool and clothes hangers crafted out of plastic bottles -- as well as unsent letters and photographs of the dead.
Relatives recall gathering outside the gates and clamouring for news of their loved ones, only to be driven away by soldiers.
They brought clothes and food for years, unaware of their loss.
Now, 16 years later, Kermi says it is critical for old wounds to be healed in the courtroom.
"We don't want our enemies to drink from the same bitter cup," he said.
The exhibition opened on Thursday and closes on Saturday. The formal day of remembrance is Friday, with special prayers planned in both Tripoli and second-largest city Benghazi.