Pope Francis is in Egypt on a visit aimed at improving Christian-Muslim dialogue, three weeks after bombing of two Coptic churches killed 45 people.
So-called Islamic State, IS, said it was behind the attacks.
As he arrived in Cairo he said his trip would be a “journey of unity and fraternity.
He is expected to meet with the Egyptian president as well as speak at the Al-Azhar University, a key centre of Sunni Islamic learning.
80-year-old Pope Francis said before the visit that he was travelling as a “messenger of peace” and, as usual, would 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 also claimed the bomb attack that killed 28 people at Egypt’s main cathedral before Christmas in 2016.
Hundreds of Egyptian Christians fled northern Sinai earlier this year in the wake of at least seven killings by suspected Islamist militants.
Apart from 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 to protect Christians before the attacks.