Pope Francis' arrival in Cuba was met at Havana's Plaza de la Revolución by 300,000 spectators who braved the heat Sunday morning to hear the Holy Father deliver Mass and talk about the need to serve.
"The importance of one person is always based on how they serve the frailty of their brothers," the pope told the assembled crowd. "In this we find one of the true fruits of humanity. Because, brothers and sisters, those who don't live to serve, do not have a life worth living."
Many waved Cuban or Vatican flags during the service, which is the first leg of a 10-day U.S.-Cuba trip.
The trip -- and the pope's words -- carry political undertones, said Carrie Kahn, NPR's international correspondent, who is covering the pope's trip to the island.
"In his gestures and some of his words, he has a political agenda, too," Kahn said. "So I think people are interpreting what they want from this visit and you're getting a little bit of it all. "
Pope Francis and former Cuban leader Fidel Castro had what a Vatican spokesman called an "informal meeting" in Castro's home Sunday afternoon following the Mass. The pope met Castro's family and even exchanged gifts.
For Castro: papal teachings. For Pope Francis: Castro's written religious opinions.
The political undertones of the pope's visit were highlighted Saturday during the his arrival speech at Havana International Airport, where he congratulated the U.S. and Cuba for their effort to normalize relations.
He called the move to create ties between the two nations "an example of reconciliation for the entire world."
"I urge political leaders to persevere on this path and to develop all its potentialities," Pope Francis said.
(Below, listen to Miami Herald political reporter Patricia Mazzei, who is in Holguín, Cuba, for the papal visit, discuss how most locals will tie in U.S.-Cuba relations when discussing the pope's visit.)
Locals echoed the pope's words. On Sunday, in front of the Santiago de Cuba Cathedral, where the pope will hold Mass Tuesday morning, 44-year-old orthodontist Sonia Acosta Gomez spoke in support of normalizing relations.
"We see it as something good because, in the words of our commander Raúl, we have to know how to coexist with someone who thinks differently from us in terms of ideology," Acosta Gomez said.
In the southeastern city of Holguín, Cuba, where the pope will travel Monday, preparations were underway this weekend along the route the popemobile will travel, said Miami Herald political reporter Patricia Mazzei, who is in Cuba for the papal visit.
She said most people in the city were looking forward to the visit, but not through the lens of religion.
"They'll say, 'He's gonna bless the city and we could really use a blessing because we've had a lot of dengue and a lot of cholera or we've had a drought and here comes the pope to bless us and for the past two days we've had rain,'" Mazzei said.
(Below, listen to Miami Herald political reporter Patricia Mazzei discuss preparations in Holguín, Cuba, for the pope's visit.)
The pope will continue his trip with a Mass in Holguín Monday and a Mass in Santiago de Cuba Tuesday. Then he will head to the U.S. to meet with President Obama in Washington, D.C., and visit New York City and Philadelphia.