US President Donald Trump has met Pope Francis for a short private audience on the third leg of his overseas trip.
The Vatican said after the meeting that there had been an “exchange of views” on several unspecified international issues, and spoke of the need to continue good bilateral relations.
The two men have already clashed at a distance on issues including migration and climate change.
Mr Trump is also meeting Italy’s president and prime minister.
Later, he will fly to Brussels for a Nato summit.
He earlier vowed to help Israelis and Palestinians achieve peace, as he ended the Middle East leg of his tour.
The US leader began his foreign trip with a two-day stop in Saudi Arabia over the weekend, urging Muslim countries to take the lead in combating radicalisation.
Mr Trump and his entourage arrived at the Vatican just before 08:30, in a the meeting that was arranged at the last minute.
The US president was greeted by Archbishop Georg Ganswein, the head of the papal household, and escorted by the Swiss Guard to the offices of Pope Francis.
Correspondents say their initial greeting was cordial. Mr Trump told the Pope “it is a great honour”.
The two men spoke privately for about 20 minutes. The Vatican said later that they shared a commitment to “life, and freedom of worship and conscience” and expressed hope that they can collaborate “in service to the people in the fields of healthcare, education and assistance to migrants”.
On international affairs, their “exchange of views” covered the “promotion of peace in the world through political negotiation and interreligious dialogue”, and highlighted the need to protect Christian communities in the Middle East.
After the meeting, they exchanged gifts. Mr Trump gave the Pope a boxed set of writings by the civil rights leader Martin Luther King.
The Pope gave Mr Trump a signed copy of a message he delivered for World Peace Day, along with some of his writings about the need to protect the environment. “Well, I’ll be reading them,” Mr Trump told him.
And the entourage?
Mr Trump was joined not only by his wife, daughter and son-in-law but also Secretary of State Rex Tillerson and National Security Adviser HR McMaster.
Both Melania and Ivanka Trump were dressed in black with their heads partially covered, in keeping with a traditional Vatican protocol that is no longer expected to be rigorously observed.
Melania, a Catholic, asked the Pope to bless her rosary beads.
What next for Mr Trump’s trip?
Mr Trump followed his visit to the Vatican with talks with Italian President Sergio Mattarella at the Presidential Palace. Prime Minister Paolo Gentiloni will later join him at the US ambassador’s residence.
This is Mr Trump’s first visit to Europe since taking office in January.
Security has been stepped up across Rome, with the areas around the Vatican City, the Italian presidential palace and the American ambassador’s residence, where Mr Trump is staying, temporarily closed to traffic.
Despite the heavy police presence, about 100 anti-Trump protesters held a rally in one of Rome’s squares on Tuesday evening.
Later on Wednesday, Mr Trump will fly to Brussels, where significant protests are expected.
For the EU and for Nato, this visit is about damage limitation with the fervent hope of establishing some kind of transatlantic chemistry, the BBC’s Europe editor Katya Adler says.
She adds that the tone in Brussels has gone from off-the-record sneering when the erratic and unpredictable Mr Trump first won the November elections, to outright concern now that the implications of his presidency have begun to sink in.
Mr Trump will end his tour on the Italian island of Sicily at the G7 summit on Friday.