You hear the gallery before you see it - a mournful folk melody, then a man's voice reciting other men's names, hometowns, and mobile phone numbers.
Then you see the five display cases.
Each one contains a piece of a shirt, tilted so you can read the names, hometowns, and phone numbers still being recited over the loudspeaker.
Some of the ink is smudged, but most of the writing is legible, and that makes these squares of fabric valuable.
They comprise a makeshift catalogue of the 82 men being held in a secret intelligence prison near the Mezzah military airport in Damascus during 2012.
They are also the heart of a new exhibition at the US Holocaust Memorial Museum in Washington: "Please Don't Forget Us", about the estimated 100,000 political activists who have disappeared during Syria's civil war.
Mansour Omari came up with the idea to memorialise his detention and that of his fellow political prisoners.
"It was in my mind all the time, 'It's my job, my task, to document the names'," Omari told Al Jazeera at an event to mark the opening of the exhibition.
In 2011, Omari started keeping a list of missing political activists for the Violation Documentation Center, a local human rights organisation.
The government had been denying reports it had anything to do with the activists' disappearances.
The centre was trying to get answers for many worried families.
"The norm in Syria, when somebody is arrested, the family gets scared to ask about their loved ones," Omari said.
"It's an atmosphere of fear. If you want to look for your son or your loved one, it also brings a threat to you."
Eventually someone decided the list keeper needed to be stopped - soldiers raided Omari's office and arrested him in February 2012.
During his detention, Omari decided the best way to get back at his captors was to keep doing what he'd been doing on the outside: Make a list of his fellow detainees, and try to get it to the outside world.
Omari says his closest friends in the prison thought it was a good idea, and so they sprang into action.
They casually gathered everyone's names and other information so no one would think to tip off a guard.
They then secretly created a mixture of their own blood and rust from their cells' iron bars to be used as the ink. The pen: Chicken bones.
One of the prisoners, Nabil Shurbaji, wrote all the names - because he had the best handwriting.
His was the dress shirt that would be used to smuggle the lists out of the prison.
Shurbaji, Omari, and the others agreed: Whoever was released first would wear Shurbaji's shirt. The scraps would be hidden inside the collar and cuffs.
The group reasoned soldiers would never search the shirt for contraband.
Miraculously, the plan worked. Omari was released in 2013.
He shared the story of the secret prison and the scraps of fabric with filmmakers Sara Afshar and Nicola Cutcher.
They featured him in their documentary, Syria's Disappeared.
Museum officials then asked Omari if he would agree to put the fabric on exhibition, so that visitors could learn what is happening right now inside Syria.
Omari agreed, because all of this would help him in his mission: Helping the families of the disappeared.
"It was very important to give the names to the families, to contact the families, to tell them, 'Your sons are alive.' Many families I contacted, they didn't know any news about their sons. It was the first time they knew anything. Mothers cried. It was also very hard work for me, contacting mothers to tell them about their sons."
But sharing the news isn't the same as getting his fellow prisoners out and back home. Nabil Shurbaji was killed by a military guard in another prison in 2015.
Back in the gallery, visitors say little as they huddle around the cases. They leave behind comment cards with the words, "Save Syria" and "Why do so many of us decide to act upon hatred?"
They're bearing witness, acknowledging what has happened, and is still happening, inside Syria.