Pope Francis is beginning a visit to Egypt aimed at improving dialogue with Islam three weeks after bomb attacks on two Coptic churches killed 45 people.
He will meet the Egyptian president and speak at al-Azhar University, a key centre of Sunni Islamic learning.
So-called Islamic State said it was behind the Palm Sunday bombings.
The 80-year-old pontiff says he is travelling as a "messenger of peace" and, despite the security concerns, will not use an armoured car.
The two-day visit is the first papal trip to Cairo in 20 years, and comes as Egypt’s Coptic Christians - who make up 10% of the country’s mainly Muslim population - face increased threats. The majority of the Copts are Orthodox, with less than 150,000 of them Catholic.
IS says it also sent a bomber who killed 28 people at Egypt’s main cathedral before Christmas. The group’s Egyptian branch says Christians are its "favourite prey".
Hundreds of Egyptian Christians fled northern Sinai earlier this year in the wake of at least seven killings by suspected Islamist militants.
’Brotherhood and reconciliation’
As well as President Abdel Fattah al-Sisi, the Pope is due to meet Sheikh Ahmed al-Tayeb, the Grand Imam of the 1,000-year-old seat of Islamic learning, al-Azhar.
He is expected to address a conference there on religious dialogue, as part of efforts to improve relations, after Egyptian Muslim leaders cut ties over comments made by Pope Francis’s predecessor Pope Benedict XVI.
The pontiff will also meet the head of the Coptic Orthodox Church, Pope Tawadros II, and walk with him to St Mark’s Cathedral, the scene of the December bombing.
In a message ahead of the trip, Francis said he wanted the visit to be "a witness of my affection, comfort and encouragement for all the Christians of the Middle East" and "a message of brotherhood and reconciliation with all the children of Abraham, particularly the Muslim world".
In a surprise TED talk earlier this week, delivered in a video, he lauded the values of humility, tenderness and hope, amid the "darkness of today’s conflicts".
A three-month state of emergency is in place in the wake of the Palm Sunday bombings, and security has been boosted around churches.
But many Copts say the government should have done more earlier to protect them, and say they are also under pressure from sectarian tensions and long-standing discrimination.
Copts in Egypt: Recent developments
April 2017:Bomb attacks at St George’s Coptic church in Tanta and St Mark’s Coptic church in Alexandria kill at least 45 people.
February 2017: Hundreds of Coptic Christians flee Egypt’s Sinai peninsula after at least seven killings by suspected Islamic militants.
December 2016: At least 28 people died when a bomb exploded at the Coptic
cathedral in Cairo during a service. IS said it was behind the attack
February 2016: A court sentenced three Christian teenagers to five years in prison for insulting Islam. They had appeared in a video, apparently mocking Muslim prayers, but claimed they had been mocking IS following a number of beheadings
April 2013: Two people were killed outside St Mark’s cathedral in Cairo when people mourning the death of four Coptic Christians killed in religious violence clashed with local residents