It was the biggest show of public protest so far, and it came just when the Egyptian regime of Hosni Mubarak had offered the greatest political concessions.
Hundreds of thousands of Egyptians overflowed giant Tahrir Square in the heart of Cairo, spilling into adjacent streets. And, in an unprecedented move, protest organizers staged a demonstration outside the Shura Council and People's Assembly (the parliament), the first time anything other than Tahrir Square had been a target of their efforts.
"It's a sign of things to come," an experienced Western diplomat said. "They're not interested in the concessions any more. They can smell blood."
Since Jan. 25, the protests have continued to build and have only been strengthened when confronted by police, the army and pro-Mubarak supporters. But just as the reformers show no signs of going away, the government is showing signs of impatience.
Vice-President Omar Suleiman said "we can't put up with" endless protests, insisting that there will be "no ending of the regime" and no imminent resignation from Mr. Mubarak, adding: "We don't want to deal with Egyptian society with police tools."
But Tuesday, on the street between the cabinet offices and the assembly - a street closed to pedestrians for most of the past two weeks - people filtered in slowly, and the protest began with perhaps 150 people at about 2:30 in the afternoon.
The army, apparently having been surprised by the move, looked on tentatively and dispatched soldiers to line the fence around the assembly grounds. But they did nothing to stop the arrival of more protesters.
Within half an hour the number grew to 500, then to a 1,000. By dusk the protesters numbered more than 2,000, all of them shouting for the dissolution of the parliament they say was elected fraudulently, and for the end of Mr. Mubarak's rule.
An army officer who, a few days ago, had tried to discourage people from going to Tahrir Square, now could be seen encouraging people to go to the square and not to protest in such a sensitive political area. No one listened.
Earlier in the day, Mr. Suleiman had announced significant concessions as a result of talks with opposition representatives on Sunday. He said that Mr. Mubarak had signed a decree establishing a judicial committee to propose constitutional amendments that would provide for free and fair elections, as well as establishing a group to monitor all proposed reforms.
Also established was a probe into last week's clashes between the protesters and government supporters as well as mass detentions of human-rights activists and journalists. The committee will refer its findings to the chief prosecutor, Mr. Suleiman said.
He also promised there would be no reprisals against protesters.
"The youth of Egypt deserve national appreciation," Mr. Suleiman quoted the President as saying. "They should not be detained, harassed or denied their freedom of expression."
The Muslim Brotherhood, which, for the first time, was included in the dialogue with the Vice-President on Sunday, called the reforms proposed so far as "partial," insisting that Mr. Mubarak must ease what it called the anger felt by Egyptians who face widespread poverty and government repression.
In a move that suggests desperation, the government on Monday announced it was giving all public servants a 15-per-cent raise, and said it would now begin hiring large numbers of the unemployed.
The Interior minister even announced that 34 political prisoners were being released.
It still was not enough for the protesters. As far as they are concerned, nothing short of the ouster of Mr. Mubarak and the dissolution of parliament will suffice.
It's become a battle strategy, says Hisham Kassem, founding editor of Al-Masry Al-Youm, Egypt's only independent newspaper. "Whenever Mubarak tries to hold his ground, they [the protesters]dig in. Whenever he yields and offers something, they advance and demand more."
"The organizers are very adept," he said appreciatively.
There is, however, no sense that the protesters realize or care about what will follow. "This is a revolution," one man said. "We want everything to change."
The resignation of the President and parliament's dissolution would leave a power vacuum. "A vacuum the army would fill," a Western diplomat said.
Many of the thousands of people in the streets for the first time said they were inspired to come out by the case of Wael Ghonim, the 30-year-old Google Inc. marketing executive who was a major impetus behind the original online campaign to launch protests.
Detained blindfolded for 12 days by the authorities, Mr. Ghonim's release came only after a special appeal by telecom tycoon Naguib Sawiris during the opposition meeting with Vice-President Suleiman on Sunday.