The Pope Francis visited parts of northern Iraq once held by Islamic State (IS) militants on the third day of his historic trip to the country.
Christians were among those targeted by IS when they seized the region in 2014, carrying out human rights abuses.
On Sunday the Pope prayed among ruined churches in Mosul, the former IS stronghold, before meeting Christians.
Celebrating Mass at a stadium in Irbil, the last big set piece of his visit, he said Iraq would remain in his heart.
Thousands of people attended the service despite Covid-19 concerns.
Iraq, which has seen more than 13,500 deaths with Covid-19 and more than 726,000 cases, has recorded a sharp rise in infections over the past month.
The 84-year-old leader of the Catholic Church and his entourage have all been vaccinated, but Iraq only received its first batch of doses last week.
The four-day trip, which began on Friday, was the pontiff's first international excursion since the start of the pandemic more than a year ago, and the first-ever papal visit to the country. He flew home on Monday morning.
Where did the Pope go on Sunday?
In Mosul he visited Church Square to pray for the victims of the war with the Islamic State group, which left thousands of civilians dead.
Surrounded by the tottering ruins of the square's four churches, he said the exodus of Christians from Iraq and the broader Middle East had done "incalculable harm not just to the individuals and communities concerned but also to the society they leave behind".
Referring to the historic region of Mesopotamia, which covered much of modern Iraq including Mosul, Pope Francis said: "How cruel it is that this country, the cradle of civilisation, should have been afflicted by so barbarous a blow, with ancient places of worship destroyed and many thousands of people - Muslims, Christians, Yazidis and others - forcibly displaced or killed.
"Today, however, we reaffirm our conviction that fraternity is more durable than fratricide, that hope is more powerful than hatred, that peace more powerful than war."
IS desecrated Christian places of worship, beheading religious statues and planting booby-trap bombs. Tens of thousands of Christians fled IS control while those who remained faced having their property stolen and choosing between paying a tax, converting to Islam, leaving or facing death.
A cross erected on Church Square in honour of the Pope's visit was crafted from wooden chairs rescued from churches across the region, Middle Eastern news outlet The National reports.
In the nearby town of Qaraqosh, the Pope met Christians in the ancient Church of the Immaculate Conception, which was once torched by IS and has now been restored.
"I can't describe my happiness, it's a historic event that won't be repeated," said Yosra Mubarak, 33, before the Pope's visit. She was three months pregnant when she left her home seven years ago with her husband and son, fleeing the violence.
"It was a very difficult journey, we fled with only the clothes we're wearing... There was nothing left [when we returned], but our only dream was to come back and here we are and the Pope is coming," she told Reuters news agency.
The Roman Catholic leader arrived by motorcade at the stadium in Irbil on Sunday afternoon, switching to a Popemobile to the delight of those waiting.
"In my time among you, I have heard voices of sorrow and loss, but also voices of hope and consolation," he told those attending.
What message is the Pope delivering?
Since arriving in Baghdad on Friday, Pope Francis has called for an end to violence and extremism and said that Iraq's dwindling Christian community should have a more prominent role as citizens with full rights, freedoms and responsibilities.
On Saturday, in a highly symbolic meeting with the Grand Ayatollah Ali al-Sistani in the holy city of Najaf, the Pope echoed this message, saying that Christians should be able to live in peace and security like all other Iraqis.
Audiences with the reclusive 90-year-old spiritual leader of millions of Shia Muslims are rare, but he received the Pope for around 50 minutes, the pair talking without face masks.
The Pope then visited the site of the ancient city of Ur, believed to be the birthplace of the Prophet Abraham, who is revered in Judaism, Christianity and Islam.
Iraq has been wracked by religious and sectarian violence, both against minorities and between Shia and Sunni Muslims too.
How vulnerable are Iraq's Christians?
People in what is now Iraq embraced Christianity in the 1st Century AD, making Christians one of the country's oldest religious communities.
About two-thirds of Iraqi Christians are Chaldean Catholics, whose Eastern-rite Church retains its own liturgy and traditions but recognises the authority of the pope in Rome.
Numbers overall have plummeted over the last two decades from 1.4 million to about 250,000, less than 1% of the country's population.
Most of those who remain live in the Nineveh Plain and Kurdistan Region in the north of the country.
Many Christians have fled abroad to escape the violence that has plagued the country since the US-led invasion in 2003 that ousted Saddam Hussein.
A US state department report on religious freedom in Iraq in 2019 found that Christians, as well as Sunni Muslims, complained of harassment at checkpoints by Shia security forces and some discrimination in education.