President-elect Mohamed Morsi arrived at Tahrir square at 5:45pm on Friday to address hundreds of thousands of Egyptians charged with classic patriotic songs and waving the Egyptian flags.
Millions others around the country watched the speech on TV screens.
A Presidential Guard unit had earlier secured the main podium where Morsi, Egypt's firsy democratically elected president after the fall of ousted president Mubarak, gave his historic 30 minute speech.
The crowd in the square which witnessed the birth of the January 25 revolution met the president-elect with wild cheers and chants of "Wake up everyone , Morsi is the president."
As the main stage played the Egyptian national anthem, the crowd roared: "Say it loud! Morsi is the president of the Republic," and "God is Great!"
But before heading to take the oath of office before the High Constitutional Court on Saturday - a step mandated by the ruling military council (after it dissolved parliament two weeks ago) and denounced by many of its opponents - Morsi pledged allegiance to the people in Tahrir.
The Brotherhood leader 'takes the oath'
Morsi led off his speech with the chant: Revolutionaries, Free, We will continue the struggle!
Morsi praised the sacrifices of Egyptian revolutionaries and said "We have showed the world what Egyptians can do, what revolutionaries can do. We stand here in the square of freedom thanks to the blood of martyrs."
"We have reached this far as a result of a long, hard struggle that lasted decades from the twenties to the thirties, from the fourties to the fifties and sixties - and you have no idea how hard the sixties were (in reference to the Brotherhood's persecution at the hands of former president Nasser) - until we finally reached January 25, 2011."
On the economic front, Morsi sought to assure the business community that he would provide security and stability.
"I promise that we will keep the economy going in Egypt, we will all finally start building and developing the country."
To reassure workers in the tourism sectors, which employs three million Egyptians, that the Brotherhood does not intend to curb the flow of foreigners into the country Morsi said he truly appreciates the centrality of tourism to the country's well being.
Meanwhile, to stress that he will not surrender any presidential powers to the ruling military council, Morsi insisted that the people are the main source of legitimacy warning that whoever challenges the people's will would lose.
"The people's power is above everything and everyone else, the police, the army, and the government. There's no power above this power."
"You bestow power unto those you choose. You deny power to those you reject."
However, Morsi tip-toed around the controversial issue of whther the Brotherhood intend to implement Islamic Sharia: "There is no contradiction between implementing the word of God and respecting the constitution, respecting the Judiciary."Morsi also stressed that Egypt will shed off its foreign dependency; will remain a free country and will make its decisions independently; and will base its foreign policy on the quest for peace.
Morsi then vowed to free all civilians who were tried in military courts since the beginning of the revolution, and also promised to fight for the freedom of the famous blind-imam Omar Abdel Rahman who serves a life sentence on terrorism charges in the United States.
"I have come here not wearing a bullet-proof vest, and I don't fear anyone but God," the president-elect stated as he pointed to his defenseless chest.
"I thank all Egyptians including those who have voted for me and those who have not. None of you will lose their rights or be excluded from contributing to the country's welfare."
"I'm ready to work with all of you: Muslims, Christians, men, women."
As the president-elect finished his address to the nation in Tahrir, crowds chants: "Field Marshal Tantawi, admit! Morsi is your president!"
"Raise your heads high! The president took the oath in the Square."
The crowd sent off the president-elect with the Chant: Down military rule! Down military rule!
Thousands wait all day for a president with powers
Thousands of Egyptians had arrived in Tahrir since the early morning hours to both take part in a million person protest against recent SCAF-issued orders to dissolve parliament as well as a constitutional addendum that gives the ruling military council new powers at the expense of an elected president.
The crowd which grew by the hour throughout the day waited to listen to Egypt's president-elect, Mohamed Morsi, who has attended Friday prayers at Cairo's Al-Azhar Mosque before heading to Tahrir Square to deliver a major speech to the nation.
After demonstrators completed the noon prayers, speakers from the main podium welcomed the election of the president Morsi and called for purging state institutions from remnants of the old regime of ousted president Mubarak.
Protesters also sang the Egyptian national anthem in a show of patriotism.
Chants calling for the downfall of the military junta and the public prosecutor resounded all day around the square. Protesters also condemned the junta's changes to the interim constiution with the chant: "Revolt, we don't want the constitutional declaration!"
Protesters also goaded the military ruler, Field Marshall Mohamed Hussein Tantawi, with the chant: "Marshall Tantawi, here comes another revolution!"
There were many Palestinian, Syrian and Libyan flags being waved in a show of support for other Arab countries undergoing revolutions and struggling for freedom.
Protesters condemned Syria's President Bashar Al-Assad and declare their prayers are with the Syrian people fighting for democracy.
Islamic preacher Safwat Hegazy hit out the Supreme Council of Armed Forces (SCAF) saying the constitution addendum it issued on 18 June 2012 "entrenches military rule."
"Egypt mustn't be ruled by 19 army generals," Hegazy, who is also the secretary general of the Revolution Board of Trustees which called the rally, told protesters in Tahrir.
"The military council's decision to dissolve the parliament should be withdrawn and the parliament should continue as it was. You should also give the new president a chance to fulfill his promises and the different political forces should unite regardless of any differences."
Hegazy also addressed the Egyptians who voted for Mubarak's last Prime Minister Ahmed Shafiq during the presidential elections, calling on them to unite with others and "let go of the past."
Meanwhile, Mazhar Shaheen, who is known as the revolution's imam, called on president-elect Mohamed Morsi to take his oath of office in Tahrir rather than in front of the Supreme Constitutional Court.
Speaking from the main sound stage at Friday's mass rally against continued military rule in Tahrir, Shaheen said Morsi should work on releasing the army officers who were imprisoned for joining protesters in Tahrir in April 2011 and those who were detained during clashes between demonstrators and army forces in Abbasiyia district, Cairo, last month.
"It's not possible to fulfill the people demands via negotiations with the military council. We should continute to protest," he told to Al-Jazeera TV afterward.
Shaheen also called on Morsi to order a re-trial of the former regime figures, some of whom were recently acquitted by Egyptian courts.
Political forces mobilise
The protest was called for by the Revolution’s Board of Trustees, formed by an umbrella group of activists in the wake of last year's Tahrir Square uprising.
The Board of Trustees Secretary-General Safwat Hegazy called on political forces to attend the rally and maintain their sit-in in the flashpoint square until the amendment is repealed; parliament's dissolved lower house is reinstated; all political detainees are released; and the SCAF promises not to interfere in the constitution-drafting process.
On Thursday, Essam El-Erian, vice-president of the Muslim Brotherhood's Freedom and Justice Party (FJP), announced that the group would participate million-man protest which has been organised under the slogan "Handover Power!"
El-Erian said that the Brotherhood and FJP were maintaining their ten-day-old sit-in in Tahrir Square until executive power is handed from Egypt's ruling Supreme Council of the Armed Forces (SCAF) to Egypt's democratically-chosen president-elect Mohamed Morsi.
The Salafist Nour Party also mobilised for Friday's protest, according to party spokesman Nader Bakar.
The moderate-Islamist Wasat Party participated in the demonstration as well.
"The Wasat Party will participate in the 'Handover Power' protest to register its rejection of the SCAF-issued constitutional addendum – which limits the powers of the president – and the dissolution of the People's Assembly," the party said in a statement late last week.
The Egyptian Current Party, a liberal-Islamist offshoot of the Muslim Brotherhood, had called on supporters and the general public to join protesters in Tahrir Square.
Some non-Islamist parties and movements are also planning to take part in the protest, including the April 6 Youth Movement.
The Revolutionary Socialists, meanwhile, led a march from Al-Fath Mosque in Cairo's Ramses district, one of several marches planned from around the capital, to Tahrir.
Protest marches were also organised in Alexandria on Friday afternoon from different starting spots converging on the military's northern zone command headquarters.
Some liberal and leftist forces boycott
Other leftist and liberal parties such as Tagammu, Karama, the Egyptian Social Democratic Party and the Socialist Popular Alliance Party have announced that they would boycot the protests accusing the Brotherhood of using Tahrir to advance narrow, and not national, political interests.
Moreover, after president-elect Morsi announced on Thursday night that he would swesr into office before the High Constitutional Court, several political forces declared that they will not take part in Friday's one million protest.
April 6 Youth Movement (Democratic Front) and the Second Revolution of Rage movement (a facebook-based revolutionary group) are among the movements that have withdrawn from Friday's protests as they considered Morsi's decision to take the oath before the High Court an acknowledgment of the amended constitution declaration recently issued by the military council which is rejected by many in Egypt.
"By doing this Morsi approves of the constitutional addendum, thus we don’t recognise him as a president of Egypt," posted the Second Revolution of Rage on their Facebook page.
The People want?
Ali Kamel, a 22-year-old Salafist protester, told Ahram Online reporters that the dissolution of parliament and the absence of a democratic constitution, along with the recently-issued constitutional addendum, will ultimately produce a "handicapped" president who cannot take decisions independently.
"We will topple the SCAF like we toppled Mubarak. Protesters in Tahrir will not accept compromises or middle-ground deals," Kamel said.
Ibrahim Amr, a Muslim Brotherhood member, said the president should take the oath of office in parliament, not the High Constitutional Court, because it has legitimacy due to its election by the people.
Amr urged the media to adopt a "neutral position" when discussing politics, pointing out that people are hugely influenced by what journalists or TV interviewers say.
Another Muslim Brotherhood member, Ahmed Ismail, believed Friday's protest chiefly aimed at re-grouping and uniting the revolutionary front against the SCAF in order to ensure their acceptance of "Tahrir's demands."
"Egypt's democracy is not in jeopardy because of Morsi's limited authority, but because the military lies outside the executive authority's control," Ismail said.
A veiled woman called Hanaa Mohamed, who claimed to be non-political, urged the international community to cooperate with the new "Islamist president" through backing the demands of the protesters in Tahrir Square.
"Mubarak's National Democratic Party is not in office anymore. The international community has to deal with Morsi if it wants to deal with Egypt," Mohamed asserted.
Bassem Ali and Hatem Maher contributed to this story