On Friday, 650 churches throughout the Madrid metropolitan area joined the five-minute tribute that began at 7.37am (0637GMT), when the first of 10 dynamite-loaded backpacks detonated on four crowded rush-hour commuter trains last 11 March.
"It will be a very sad day, especially for the relatives of the victims," said Amaya Sistiaga, a 35-year-old office worker, standing outside the Church of St. Teresa in Spain's capital.
"It really could have happened to any one of us. That is the truth," said Victoria Martinez Montes, a 70-year-old retiree. "More than remember, what we should do is try to help those who survived because those who are gone are now with God."
Flowers and candles
At the El Pozo station - where 67 people died on a double-decker train, the deadliest of the four scenes of carnage - people brought flowers and candles to a makeshift memorial.
One man tossed red and white carnations onto the railroad tracks.
Another, an emergency medical worker who attended to the dying the day of the attack, came wearing his uniform, a yellow jumpsuit, to pay his respects.
"A year ago they took something away from us"
"I will never forget the image of what happened here," said the 42-year-old worker, who identified himself only as Paco. "I still remember the smell of gunpowder. Finding pieces of bodies on the platform, the image of a boy's head on a bench."
As he spoke, a text message beeped on his cell phone. It was from a rescue-worker colleague and said "a year ago they took something away from us."
Friday's main memorial act will be silent - a short noontime (1300GMT) ceremony at a park where 192 olive and cypress trees have been planted in honour of the people killed on the trains and one special forces officer who died three weeks later while trying to arrest suspects.
The train attacks were claimed in videotapes by a group that said it acted on al-Qaida's behalf in revenge for Spain's troop presence in Iraq.
On Thursday, Spain's Parliament observed five minutes of silence - only the mournful strains of a cello could be heard in the chamber.
Lawmakers at the Congress of Deputies stood grim-faced by their seats.
"That ominous day sowed pain and desolation in the city of Madrid," the legislature said in a statement read out before the tribute. "It was a direct blow at our life in peace and freedom, and broke the hearts of all our citizens."