Meeting in plain view of the Casa Rosada, or the Pink House, the name for the Argentine presidential place, since April 30, 1977.
Demanding a full accounting of, and justice for, their sons and daughters who were disappeared during Argentina's "Dirty War" that lasted from 1976 to 1983.
The government put the figure of the number of people who were tortured before being killed and having their bodies disposed of in rural areas or unmarked graves at about 9,000 to 11,000, but the mothers say the total is closer to 30,000.
They have marched during the 1978 World Cup that Argentina hosted and won.
They have marched during the transition to democracy that saw President Carlos Menem sign an amnesty law that absolved the leaders of the military regime of their crimes.
They marched during the split of their group into two-those who accepted money from the government as partial compensation for the deaths of their loved ones and those who continue to call for a full accounting for what happened.
They have marched when President Nestor Kirchner overturned the amnesty law and opened the door for more prosecutions of top-ranking generals.
And they marched today.
Dunreith and I arrived at the plaza this afternoon shortly after 3:00 p.m.
The sun was strong, the sky nearly cloudless.
We had already absorbed some of the city's ample, European-based charm, walking past classic-looking stone buildings on the wide boulevard on the way to El Ateneo, a magical former theater turned bookstore/cafe.
Two of the mothers were on the periphery of the circle where the women march standing under a blue tent, where they sold books, pens, and other materials about the disappeared.
I asked if they could answer some questions about their experiences.
They were working, they said, and couldn't took.
The Mothers of the Plaza de Mayo-Founding Line, the group that had accepted financial compensation from the government, marched first.
Five women, including two mother wearing white head scarves, toted a white banner with the group's name on it as they marched around and around the square.
Younger supporters marched with them. A half dozen carried black and white pictures of their loved ones with them.
This included a woman with a bullhorn who called out disappeared people's names.
"Presente," the group answered in unison.
Present.
Even though their loved one were not physically there, the mothers were saying that they were present.
The Mothers of the Plaza of Mayo Association went next.
Their group was larger, and led by ten women also wearing white head scarves.
They carried a blue banner with white letter that said, "Until Victory Always Beloved Children."
Their scarves had the words, "Appearance with life, the disappeared, Mothers of the Plaza de Mayo" stitched in a blue cross-stitch.
Many of the mother wore glasses and walked with a slow stiffness.
But there was nothing stiff about the way many jointed the crowd behind them in waving their fists, chanted and sang songs about the mother having power and being in the square, about their work being a national project.
Around and around they marched, adding yet another chapter to their ceaseless struggle of witness and justice.
They stopped after about half a dozen laps before standing next to the tent.
The crowd applauded the madres loudly before Evel de Petrini addressed them.
De Petrini, who has searched for her son since the group began, spoke about Sunday's elections.
She said the voters had to evaluate who would actually do what they said they would do before urging everyone to vote for Christine Kirchner, the current president and widow of the former leader.
The crowd cheered again.
Her speech concluded and the group mingled before starting to disperse.
Many of the mother filad back into the white van with the name of the group painted on the side.
Like several others, I stayed outside the roped area that had been set up to give the mothers space to walk into the van.
It had the effect of making them look like stars walking down the red carpet.
A few lone fans clapped again as they went by.
A pair of mothers hugged.
The two women underneath the tent kept selling.
Martha Minow wrote in the introduction to her book Between Vengeance and Forgiveness that no act by the government can bring closure to the kind of wounds these women have experienced because any gesture is by definition insufficient.
But they are also necessary.
These women, all of whom are aging, some of whom are physically frail, have not yet achieved the justice they seek.
But they've also never given up.
In their fierce and unwavering commitment, they've not only honored the memory of their murdered children whose political ideas many have begun to adopt.
They've also provided an example for people across the globe to follow.
They've helped overturn a law that shielded the evildoers from impunity.
They've helped open the door for those people to be punished for what they did.
Any they've shown what is possible from people with comparatively meager financial resources, but a righteous and wounded sense of justice.
