HO/AFP/Getty Images

Pope Benedict XVI met with Cuba's revolutionary icon Fidel Castro Wednesday, the last day of a trip to bolster the Roman Catholic church's relationship with the Communist government.

HAVANA -- Pope Benedict met with Cuban revolutionary icon Fidel Castro after saying mass in Havana Wednesday, Vatican spokesman Father Federico Lombardi said.

The meeting comes toward the close of the pope's three-day visit to the communist-run island, during which the pontiff called for greater freedoms and a bigger role for the Roman Catholic Church in Cuban society.

Fidel Castro said Tuesday in one of his columns, or "Reflections," published online that he would meet briefly with the pope "with pleasure." Castro is now mostly retired but still occasionally writes columns and meets with visiting leaders.

According to the Vatican spokesman, this is the first time since his illness that Castro has gone out to call on a visitor. Heads of state usually come to see him.

Castro was dressed in a blazer with what looked like a scarf wrapped around his neck. He was accompanied by his wife and two adult sons.

According to the Vatican, the two men had an animated dialogue. They joked about their age, and the pope told Castro: "I'm old, but I still know how to do my job."

Castro told the pope he had been following his visit on television and asked about changes in the Catholic liturgy since his days in Jesuit schools, according to Lombardi.

In his prepared departure remarks, the pope criticized the U.S. embargo, saying that the task of building a society of broad vision is "worsened when restrictive economic measures, imposed from outside the country, unfairly burden its people."

Earlier Wednesday, before his meeting with Castro, the pope urged Cubans to search for "authentic freedom" as he celebrated an open-air Mass for some 300,000 people in Havana's Revolution Square.

Crowds began gathering during the night to hear the leader of the world's 1.2 billion Catholics speak in the sprawling plaza that Castro, 85, used to fill with big crowds and fiery revolutionary rhetoric in hours-long speeches.

Surrounded by 10-story high images of Castro's revolutionary comrades Ernesto "Che" Guevara and Camilo Cienfuegos, the pope read a sermon that continued one of the main themes of his trip -- that Cuba should build a more open society, based on truth, justice and reconciliation.

"The truth is a desire of the human person, the search for which always supposes the exercise of authentic freedom," the pontiff said.

In an apparent dig at Marxism, the pope also said some "wrongly interpret this search for the truth, leading them to irrationality and fanaticism; they close themselves in 'their truth,' and try to impose it on others."

Delicate dance for Pope Benedict in Cuba

Hours before the Mass began, the area was filled with people waving Cuban flags and wearing broad hats and holding umbrellas to shield them from the sun.

They wildly welcomed the successor of the much-beloved Pope John Paul, who made a historic, groundbreaking trip to Cuba in 1998 and preached from the same square.

'Message of love'
Benedict, wearing purple vestments, read out a virtual shopping list of rights that the Church still lacked in Cuba as President Raul Castro, Fidel's younger brother, sat in the front row. Both of the Castro brothers were educated by Jesuits, the worldwide Catholic order.

"To carry out this duty, she [Cuba] must count on basic religious freedom, which consists in her being able to proclaim and to celebrate her faith also in public, bringing to others the message of love, reconciliation and peace which Jesus brought to the world," he said.

PhotoBlog: Pope Benedict celebrates mass with 300,000 Cubans

While Benedict acknowledged "with joy" the great improvements since John Paul's visit, he added that "nonetheless, this must continue forwards, and I wish to encourage the country's government authorities to strengthen what has already been achieved and advance along this path of genuine service to the true good of Cuban society as a whole."

The faithful could be "at once a citizen and a believer", the pope assured the government, adding that strengthening religious freedom consolidates social bonds and lays the groundwork for securing the rights of future generations.

"This is why the Church seeks to give witness by her preaching and teaching, both in catechesis and in schools and universities," he said.

The mass was also watched by Miami's Cuban Catholics, including a crowd of about 80 people at the Ermita Caridad Church in Coconut Grove, Fla., NBC 6 Miami reported.

Since his arrival in the eastern city of Santiago, the pontiff has spoken of Cuba's need for reconciliation and a more open society, with the Church at its side as a buffer against "trauma" or social upheaval.

"We hope he brings peace ... and an end to the U.S. embargo," said Belkis Martin Rodriguez, 49, walking to Revolution Square dressed in jean shorts, with her mother and 8-year-old son.

Asked if she hoped the visit would bring reconciliation between the communist government, dissidents and exiles in Miami, she said, "Let each remain in their own place. If people left for Miami, let them stay there and be happy. Let the Church stick to its own field, religion, and let the government handle the politics."

Pope, Raul Castro meet, but Cuban official vows no political reform

In talks on Tuesday with Raul Castro, the pope urged a bigger role for the Church and asked that the government consider making Good Friday, the day Christians commemorate Christ's death, a national holiday. Good Friday is less than two weeks away. Fidel Castro reinstated Christmas as a holiday ahead of the landmark visit of John Paul that helped improve long-strained Church-state relations.

Jailed U.S. contractor
The Vatican during Tuesday's meetings also made several "humanitarian requests," without giving details but possibly having to do with political prisoners or jailed American contractor Alan Gross, who is serving a 15-year sentence for illegally installing Internet networks on the communist-run island.

The State Department would be very grateful if the Pope were to raise the issue of Gross during his visit, spokeswoman Victoria Nuland said.

"We obviously are hopeful that the Pope will continue to be strong on all of the human rights issues in Cuba, religious freedom, and it would be a very, very good thing if the Cuban government were to take this opportunity to release Alan Gross," Nuland said.

At a time when Church-state relations are the warmest they've been since the 1959 revolution, Benedict has not been afraid to poke the Cuban government in some sensitive places.

On the flight to Mexico beginning his trip on Friday, the pope said communism "does not correspond with reality" and that Cuba needs a new economic model.

However, Marino Murillo, a vice president in the Council of Ministers and the country's economic reforms czar, made it clear that change to Cuba's one-party political system is not in the works.

"In Cuba, there won't be political reform," he said at a news conference at Havana's Hotel Nacional, the international press center for the pope visit. "We are talking about the update of the Cuban economic model to make our socialism sustainable."

Murillo said the government welcomed all ideas, but would not allow them to be imposed on the country.

In response, Vatican spokesman Father Federico Lombardi said "the Church is not trying to impose solutions. We know it is a long road and that the history of Cuba is complex."

Reuters, NBC News and msnbc.com staff contributed to this report. 

More from msnbc.com and NBC News:

• Teen rescued after 28 days adrift at sea
• Grumble, grumble: Brits revel in gloom ahead of Olympics
• Afghan abuse victims jailed over 'moral crimes'
• Man cuts off foot, throws it in furnace to avoid job assignment
• Turmoil builds in China's Tibetan regions
• French rail company to pay out after delays cost commuter job
• World's cities to expand by twice the size of Texas by 2030

Follow us on Twitter: @msnbc_world