Hundreds of thousands rallied in the square on this 11th day of protests against Mubarak's 30 years of authoritarian rule, The New York Times reported. The protests in the square were largely peaceful after violent clashes Thursday.
The protesters carried a sign, written in English, saying "The people demand the removal of the regime," according to CNN. They also chanted slogans like "He leaves, we don't leave" and "The blood of the martyrs will not be forgotten."
Volunteers and soldiers searched those entering the square for weapons, BBC News reported. The searches appeared orderly, with separate lines for men and women.
Less than half a mile away, tensions were much higher, with gunfire ringing out as supporters and opponents of Mubarak clashed.
Mohamed ElBaradei, the Nobel laureate and former U.N. official who returned to his native Egypt last week to join the protests, told reporters today that Mubarak "should hear the clear voice coming from the people and leave in dignity." He called it a "question of trust, and the trust is gone," The Associated Press reported.
There were conflicting signals about what, if any, role ElBaradei envisions for himself. He told an Austrian newspaper that he will not be the one to replace Mubarak. "No, I will not run," Der Standard of Vienna quoted ElBaradei as saying, according to MSNBC. "The best I can do to be an agent for change is to act as one. I am an agent of change."
Egypt's defense minister, Mohamed Hussein Tantawi, and other senior army officials visited the square after dawn, in a sign that today's demonstration is sanctioned by the military.
Also spotted in the square was Amr Moussa, the respected head of the Cairo-based League of Arab States, the English-language website of Egyptian daily Al-Masry Al-Youm reported.
In Alexandria, thousands marched from the city's central mosque in protest, according to CNN.
"This is a great revolution and the whole regime, the entire system needs to be changed. The revolution must continue until all objectives are met," the mosque's imam told the crowd.
Smaller pro-Mubarak demonstrations across the country also were reported.
The revolutionary fervor was not so evident in other parts of the Middle East today. In Syria, the rainy streets of Damascus were quiet this afternoon, with no protesters sighted, Agence France-Presse reported. And in Yemen, tens of thousands loyal to President Ali Abdullah Saleh flooded the capital's square, prompting opposition demonstrators to move a planned rally to a university about a mile away, Australia's Herald Sun reported.
More attacks on news media covering the unfolding drama were reported today, with Al-Jazeera saying in a Twitter message that the network's office in Cairo had been stormed and trashed, CNN reported.
Soldiers in Tahrir Square appeared to be wearing fresh uniforms and helmets and seemed to patrol with new resolve, checking protesters' ID cards but allowing them to pass into the square. Tanks mobilized to new positions set back from the fray.
The army, balancing support from both protesters and ruling politicians, has been in a precarious spot for days. At first, soldiers said they would not fire upon their countrymen, then stood aside while violence erupted, citing an absence of orders to intervene. On Thursday, troops set up a buffer zone to protect anti-government demonstrators from pro-Mubarak thugs.
"We're expecting them to attack us again," Khalid Abdalla, a protester who said he hasn't left Tahrir Square in 48 hours, told the BBC.
Mostly men but some women carried baskets of bread, food and water into the square to hand out to protesters who camped out all night. Today's demonstration, bolstered by millions of Egyptians streaming out of mosques after noon prayers, could be a long one.
"Today is by far the largest number of people we have had," Abdalla said.
Protesters chanted, prayed and sang Egypt's national anthem in unison. Then they hoisted a man in a wheelchair above the swaying crowd, who pumped his fists in solidarity. Volunteers organized makeshift clinics and security checkpoints, and no pro-Mubarak supporters were allowed in, The Guardian reported.
"The scene of Tahrir right now is incredible. Millions of people praying. Reverence. Very powerful. It looks like Mecca in haj," a prominent Egyptian blogger who goes by the name of Sandmonkey wrote on Twitter.
It was a stark change of mood from less than 24 hours earlier, when pro-Mubarak supporters suspected of being plainclothes government agents attacked unarmed demonstrators and journalists. The country's health ministry said eight people have been killed and more than 800 wounded.
Meanwhile, American diplomats are discussing the possibility that Mubarak could resign immediately and hand power to his deputy, Omar Suleiman, Egypt's longtime spy chief, who has a reputation for severity at home but allegiance to the U.S.
British Prime Minister David Cameron said Egypt needs to show there is a "clear, credible, transparent path toward transition," and urged other European leaders to declare that they will support a peaceful transfer of power, the BBC reported.
But Italian Prime Minister Silvio Berlusconi, mired in his own scandals involving accusations of womanizing and an alleged prostitution ring, defended the Egyptian leader, calling him the "wisest of men."