Devout Muslims, committed socialists, and hordes of formerly apathetic young people made common cause there against Mr. Mubarak and his security forces, insisting they'd found a unity that would change Egypt forever.
Ramy Essam was one of them. When the uprising began, the aspiring singer was drawn to Tahrir from his hometown of Mansoura, about 70 miles northeast of Cairo. When government thugs tried to sweep protesters from the square, Mr. Essam was in the thick of the scrum, fighting back at the barricades.
When the violence subsided, the movie-star-handsome 23-year-old strummed his guitar. A call-and-response song he wrote incorporating anti-Mubarak chants became a Tahrir Square anthem.
"I'd always ignored politics – I thought it was all rigged," he told me on Feb. 12, the evening after he and his comrades pushed Mubarak from power. "But this was a chance to do something for my country, to help change things. I couldn't stay away."
But even as he spoke of unity and hope, of his conviction that democracy was assured and his desire to get back to his music career, the complicated business of creating post-Mubarak Egypt was just getting under way.
Essam's experiences in the months since that day are a product of powerful forces inside Egyptian society – and much of the region – that mean the promises of the Arab Spring are far from fulfilled. While the bloody crackdowns against democracy activists by Syria's Bashar al-Assad and Libya's Muammar Qaddafi are getting most of the attention, Egypt is struggling to shed the everyday kinds of intimidation and thugishness that dictators use to secure their rule.
On March 9, during a protest to keep pressure on the military rulers now controlling the country, Essam was rounded up with fellow demonstrators at Tahrir and taken to the Egyptian Museum, which the Army had been using as a makeshift jail. He was beaten and given electric shocks as punishment for taking part in the protest. Dozens of other activists have been tortured since Mubarak's fall as well. Female protesters have been forced to take so-called virginity tests and military courts have been used to silence critics.
In Egypt, Tunisia, the hard work begins
These incidents are a reminder that the authoritarian habits of decades aren't going to vanish on their own.
In Egypt and Tunisia, there are still security states reliant on torture and coercion that need dismantling, and allies of Mubarak and Tunisia's Zine El Abidine Ben Ali still fight rear-guard actions.
Qaddafi and Assad, meanwhile, have taken the lessons of Egypt and Tunisia to heart – and plunged their countries into bloody civil wars. Saudi Arabia, the Gulf's preeminent financial and authoritarian power, is using its money and troops to make sure the spark of democracy doesn't ignite in fellow monarchies.
The House of Saud participated in the bloody crackdown on activists in Bahrain, where 1,500 of its troops helped sweep protesters from the street. The Bahraini monarchy then destroyed Pearl Roundabout, a focal point of protests. "No Tahrir Squares here," was the message.
At home, Saudi Arabia's King Abdullah has promised vast new payouts to citizens and reempowered some of the most reactionary elements of the religious establishment to lash out at any liberalizing influences. (For more on Saudi Arabia's efforts to slow political change read The House of Saud strikes back).
"We know that Arabs want democracy, and they're willing to fight for it and die for it," says Shadi Hamid, who studies democratic reform in the Middle East at the Brookings Doha Center. "The short, rapid nature of the Egyptian and Tunisian revolutions was something of a fluke. It's usually not that easy … [regional leaders] saw the mistakes Mubarak and Ben Ali made, and are determined not to make them."
Mr. Assad isn't taking any chances. At least 1,600 Syrians have been killed in a crackdown on democracy protests in Syria, which has involved torturing to death regime critics as young as 15. Troops have been sent into towns to contain protests before they start, and the situation has increasingly veered toward civil war.
Assad, who watched as Mr. Ben Ali and Mubarak offered tepid concessions while a populace fed up with dictatorship grew braver, has chosen the route of state terror – which has been an effective tool of social control for his family in the past. In 1982, his father and predecessor, Hafez al-Assad, had tens of thousands killed in the city of Hama after it backed an Islamist uprising against his rule.
Sadly, brutality has worked: Assad held power for 30 years, with his son becoming president in 2000 after Hafez's death. (Editor's note: The original version misstated the length of Bashar al-Assad's rule.)
But even when dictators do fall, the hard work of fundamental reform remains. Egypt is now negotiating its way toward a true political transition under the shaky guidance of a military junta.
Politicking and ideology were absent from Tahrir Square in the euphoria just before Mubarak's fall. That was what allowed Coptic Christians, Islamists, and liberals to strive for the common goal of removing Mubarak. When he was gone, however, politics quickly reentered the fray.
The moment when politics reemerged
The day after crowds in Egypt learned they had toppled one of the world's longest-standing dictators, Essam returned to his stage for another performance. A string of women in head scarves quietly made their way toward him, followed by a group of young men who roughly and forcefully segregated the crowd by gender.
A woman in a head scarf jumped on stage, grabbed the microphone, and began an accusatory religious harangue about the sanctity of prayer time and the importance of being a good Muslim. She resisted efforts to get her to desist, and furiously denounced the boos that started to pour from sections of the crowd.
Essam, in his ponytail and jeans, looked on bemused. After half an hour, the woman gave up and the show went on – though with a segregated crowd watching.
In the following months, the politics have ramped up. The Muslim Brotherhood, the once-banned Islamist group that operated in the background of the revolution, is pushing for more power in a country where they've been ruthlessly hounded for generations. Despite that, they have the best political organization of any group vying for power.
How they perform in this fall's elections – and what they do with any power they get – will be eagerly watched for signs of how political Islam evolves in the region when allowed to compete openly.
Marc Lynch, a political science professor at George Washington University, says that he's "cautiously optimistic" about Egypt's transition and says fears of an Islamic state emerging in Egypt any time soon are off the mark.
"There's a really broad consensus in the country for democratic elections and some form of representative government," says Mr. Lynch, who recently returned from a research trip to Cairo. "It's hard to believe anybody could openly take a position against that at this point."
The Brotherhood is "extremely cognizant of another Algeria or a Gaza. They are hyperaware of what happened in those cases," he says. In Algeria, when Islamists won a free election in 1991, the country's military plunged the country into a bloody civil war. When Hamas won Palestinian elections in 2006, a brief civil war led to the splintering of the Palestinian territories.
In the case of Egypt, Brotherhood leaders have promised not to contest more than 49 percent of the seats available in upcoming elections, guaranteeing they won't have an outright majority.
"They don't want to provoke the international community. They don't want people to freak out," says Mr. Hamid. "The last thing Islamists want is to abort this opportunity that not only they have, but Egypt has."