Tens of thousands of people converged on the heart of Cairo today, responding to a call for a million Egyptians to unite in the largest protest in a week of unceasing demands for President Hosni Mubarak to leave after nearly 30 years in power.
A stream of protesters arrived in Tahrir (Liberation) Square at checkpoints guarded by protesters and the army, which promised last night that it would not fire on protesters.
The announcement was a sign that army support for Mr Mubarak may be unravelling as momentum builds for an extraordinary eruption of discontent and demands for democracy in the United States' most important Arab ally.
"We are not going anywhere until Mubarak leaves," said Mohammed Abdullah, a 27-year-old aviation engineer.
Mr Mubarak would be the second Arab leader pushed from office by a popular uprising in the history of the modern Middle East.
The loosely organised and disparate movement to drive him out is fuelled by deep frustration with an autocratic regime blamed for ignoring the needs of the poor and allowing corruption and official abuse to run rampant.
After years of tight state control, protesters emboldened by the overthrow of Tunisia's president last month took to the streets on January 25 and mounted a relentless and once unimaginable series of protests across this nation of 80 million people - the region's most populous country and the centre of Arabic-language film-making, music and literature.
Soviet-era and newer US-made Abrams tanks stood at the roads leading into Tahrir Square, a plaza overlooked by the headquarters of the Arab League, the campus of the American University in Cairo, the famed Egyptian Museum and the Mugammma, an enormous winged building housing dozens of departments of the country's notoriously corrupt and inefficient bureaucracy.
Working-class men in scuffed shoes and worn cloth pants stood alongside women in full-face veils who chanted, "The people want to bring down the regime!"
For days, army tanks and troops have surrounded the square, keeping the protests confined but doing nothing to stop people from joining. The guns of many of the tanks pointed out from the square.
Military spokesman Ismail Etman said the military "has not and will not use force against the public" and underlined that "the freedom of peaceful expression is guaranteed for everyone".
He added the caveats that protesters should not commit "any act that destabilises security of the country" or damage property.
The protests appeared to be better organised today.
Volunteers wearing tags reading "Security of the People" said they were watching for government infiltrators who might try to instigate violence.
"We will throw out anyone who tries to create trouble," one announced over a loudspeaker.
Authorities shut down all roads and public transport to Cairo, security officials said. Train services nationwide were suspended for a second day and all bus services between cities were halted.
All roads in and out of the flashpoint cities of Alexandria, Suez, Masnoura and Fayoum were also closed.
The protesters - and Barack Obama's administration - roundly rejected Mr Mubarak's announcement of a new government yesterday which dropped his highly unpopular interior minister, who heads police forces and has been widely denounced by the protesters.
Abdel Rahman Fathi, 25, said his friends from the provinces were taking private cars to the square.
"The goal is to oust the regime," he said. "Every day we try to increase the number."
Two stuffed dummies representing Mr Mubarak were hung from traffic lights at the square. On their chests was written: "We want to put the murderous president on trial."
The faces of the dummies were covered with the Star of David, an allusion to many protesters' accusation that Mr Mubarak is a friend of Israel, which continues to be seen by most Egyptians as their country's arch-enemy more than 30 years after the two nations signed a peace treaty.