Thousands of Egyptians flooded the streets on Friday in a show of opposition to Islamist President Mohamed Morsi and his Muslim Brotherhood after a week of a wave of deadly unrest swept the country.
Protesters braved a rare Cairo rainfall to march to Tahrir Square and the presidential palace, chanting "Freedom!" and "Morsi is illegitimate!"
Thousands also marched in the Mediterranean port of Alexandria and the canal city of Port Said, which was at the heart of last week's clashes after 21 residents were sentenced to death over football-related violence a year ago.
The opposition National Salvation Front (NSF) joined rival factions on Thursday in condemning the violence and supporting efforts for a national dialogue.
But the coalition of mainly liberal and leftist groups also called Friday's protests demanding a unity government and amendment of the Islamist-drafted constitution which polarised the nation when it was passed in December.
The rallies come after a week of deadly unrest left nearly 60 people dead, in the worst political crisis since the president came to power last June.
Morsi is accused of betraying the revolution that brought him to the presidency and of consolidating power in Brotherhood hands.
In a statement, the NSF said Egyptians would demonstrate nationwide against "a regime that seeks to impose its will on the people and is managing the country in the interest of the Brotherhood."
Top Islamic scholar Grand Imam Ahmed al-Tayyeb chaired talks Thursday between liberal opposition heads, Islamists, youth groups, independents and church members at the headquarters of Al-Azhar, Sunni Islam's highest seat of learning.
They signed an Al-Azhar document vowing to support "a serious dialogue" and "condemn all forms of violence and incitement to violence," and stressing "the responsibility of the state and its security apparatus to protect citizens."
Opposition and NSF leader Mohamed ElBaradei, a former UN nuclear watchdog chief, praised the Al-Azhar talks.
"We come out of these talks with some sort of optimism" despite "the difficult challenges ahead," he told reporters.
"We will do whatever we can with goodwill to build the trust of the Egyptian people."
Saad al-Katatni, head of the Brotherhood's Freedom and Justice Party, stressed the need for compromise.
"There is no solution to the problems in our path to democracy without dialogue... Dialogue must have guarantees but no preconditions," he told journalists.
"All topics are up for discussion and all participants said they were ready for compromises."
It remains to be seen whether the Al-Azhar document will carry any weight on the street.
Even with few concrete points agreed, Thursday's talks marked a blow for Morsi whose calls for dialogue were snubbed by the opposition only last week.
In a statement, the presidency welcomed the document as "an important step on the road to re-establishing stability."
The interior ministry said it respected "the right to peaceful protest," but urged all political forces to ensure "a peaceful and civilised" day, a spokesman said.
Egypt has been gripped by unrest since rallies last week marking the second anniversary of the uprising that toppled president Hosni Mubarak.
The protests turned violent on Saturday after a Cairo court sentenced 21 Port Said residents to death for their involvement in clashes in a football stadium riot that killed 74 people.
Friday's protests also mark one year since the deadly events in Port Said.