A poster featuring Pope Francis and a welcome message decorates the back of a tricycle taxi in Havana, Cuba, Friday, Sept. 18, 2015. Francis will visit Cuba from Sept. 19-22, before arriving in the United States, making him the third pontiff to visit the island nation.

HAVANA (AP) — Pope Francis began a 10-day trip to Cuba and the United States on Saturday, embarking on his first trip to the onetime Cold War foes after serving as secret mediator of their historic rapprochement. He will be offering a show of solidarity with Cubans and delivering the message in the United States that Hispanics are the bedrock of the church there.

The first Latin American pope will become the first pontiff to address the U.S. Congress and will also proclaim the first saint on U.S. soil by canonizing the missionary, Junipero Serra.

With his arrival in Havana, where he was greeted by President Raul Castro, he became the third pontiff to visit Cuba in the past 17 years — a remarkable record for any country, much less one with a small community of practicing Catholics.

It’s largely unknown territory for the 78-year-old Argentine Jesuit, who has never visited either country and confessed that the United States was so foreign to him that he would spend the summer reading up on it. His popularity ratings are high in the U.S., but he also has gained detractors, particularly among conservatives over his critiques of the excesses of capitalism.

Such criticisms have endeared him to Castro, who vowed earlier this year that if Francis kept it up, he would return to the Catholic Church.

But Francis has also been on record criticizing Cuba’s socialist — and atheist — revolution as denying individuals their "transcendent dignity."

The visit began in Havana, where he is being greeted as something of a hero to Cubans who rightly credit him with helping restore diplomatic relations between the United States and Cuba. Francis issued a personal appeal to Presidents Barack Obama and Raul Castro last year to end 50 years of animosity, and later hosted the Cuban and U.S. delegations to finalize the deal. Read more msn.com