It is unclear when Melania Trump became Catholic.
Mr Trump's daughter Ivanka after meeting victims of trafficking in Rome.
Prime Minister Charles Michel said he insisted that Trump should unequivocally back the Paris Agreement on climate change and honour the USA commitment to multilateral trade agreements, two issues about which Trump has raised doubts. She responded with a chuckle that she did.
Apparently, this was something of a inside joke between the pope, who loves Slovenian food, and the first lady, who is Slovenian.
In a lighter moment, Francis referred to Trump's imposing bulk by asking his wife Melania, "What do you feed him on?" Memorial's "Stone of Hope" statue in Washington, DC, and a bronze sculpture named, "Rising Above", which the White House said represents "hope for a peaceful tomorrow".
As the Trump's disembarked Air Force One in Italy Melania wasn't interested in the US President's touch.
The Pope's gift left no questions about its symbolism, presenting Trump with an olive tree medal crafted by a Roman artist that the Pope said symbolizes peace.
"Well, I'll be reading them", Mr Trump said.
We can't wait to see how the Trumps top this.
Trump gave Francis a boxed set of five first-edition books by Martin Luther King Jr. and a bronze sculpture titled "Rising Above", representing a peaceful tomorrow and created to evoke the values of unity and resilience. He is something. He is really good. "We had a fantastic meeting". But it was his meeting with Pope Francis that drew the most anticipation due to their previous "disagreements" over immigration, refugees, and the environment. It also opposes his plan to build a wall on the United States border with Mexico.
As he completed the visit with the pontiff, President Trump told him, "I won't forget what you said".
Trump's visit to the Vatican has been met with a number of smaller protests.
In Brussels, on Thursday, Trump drew more unwanted attention when he appeared to push aside a world leader at a Nato Summit.