Pope Francis met Fidel Castro yesterday (Sunday) at the Cuban revolutionary leader's home in Havana, after an outdoor mass attended by tens of thousands of people in the capital.
The two men held a "friendly and informal conversation" for around 40 minutes, said the Rev Federico Lombardi, the Vatican spokesman.
They also exchanged gifts. Fidel Castro gave the Pope a book entitled Fidel and Religion, based on conversations between the Cuban leader and a Brazilian priest, in which he speaks about his views on Catholicism and his education in a Jesuit school.
The former revolutionary leader wrote a dedication inside the book: "To Pope Francis, with the admiration and respect of the Cuban people."
The Pope gave Fidel a collection of books on theology as well as a volume written by a Jesuit who taught the former guerilla leader at the Catholic school he attended as a child.
Pope Francis was also due to meet Castro's brother, President Raul Castro, who took power when Fidel stepped down because of ill health in 2006.
Before meeting the Castros, the Latin American pontiff held Mass for tens of thousands of Cubans in Havana's Revolution Square, dominated by a giant likeness of Che Guevara.
The Pope was driven through the crowds in his white vehicle, pausing to kiss children who were held up to him.
There were high hopes among many Cubans that the Pope's visit would spur the Castro regime towards enacting further reforms in the country, where many survive on an average monthly wage of $25 (pounds 16).
But the message delivered by the Pope in two addresses to the large crowd was more pastoral than political, as he refrained from criticising the Communist government.
His only overt political statement was to call for reconciliation in Colombia between the government and Farc, the guerrilla group. The two sides have been holding peace talks in Havana for more than two years in an attempt to bring to a close South America's longest-running armed conflict.
"May the blood shed by thousands of innocent people during long decades of armed conflict... sustain all the efforts being made, including those on this beautiful island, to achieve definitive reconciliation," he said.
Cuban police detained some dissidents who appeared to be trying to distribute leaflets during the service. Three people were dragged away by the officers, in the first protest of the Pope's four-day tour of Cuba, which will include visits to the eastern cities of Holguin and Santiago.
Political opponents of President Raul Castro's regime are regularly subjected to harassment and intimidation.
While the crowds at the Mass cheered the Pope, many other Cubans were less impressed by his visit. They say there have been few benefits from the last two papal visits - that of John Paul II in 1998 and Benedict XVI in 2012.
Alex Ferdinand, who owns a restaurant in Havana's historic centre, said: "For me it makes no difference whether he comes here or not. I hope he can change the situation politically but it depends on the next US government."
Raul Garcia, a taxi driver, said: "We've had two papal visits already and nothing changed for ordinary people."