Pope Francis met with former Cuban leader Fidel Castro on Sunday after celebrating Mass for thousands of worshippers at Havana’s famous Revolution Plaza.

Vatican spokesman Federico Lombardi told journalists that Vatican officials had in fact been in contact with some dissidents, but that they had not managed to arrange a meeting.

Thousands of people greeted his motorcade in Santiago, underlining how his key role in brokering the thaw between Cuba and the U.S. – the next destination on his most high-profile trip to date – has made him immensely popular on the island. Francis told the Cubans that they, too, should allow themselves “to slowly overcome our preconceptions and our reluctance to think that others, much less ourselves, can change”.

“We want to ask the pope for peace, tranquility, unity around the world and to help us get back the base”, said 54-year-old builder Noel Perez, from the town of Caimanera, near the base.

Francis’ homily also reflected a very personal story of his own faith and willingness to embrace change.

He said they should continue to be “at the service of the frailty of your brothers and sisters” and “not neglect them for plans which can be seductive, but are unconcerned about the face of the person beside you“.

Pope Francis was finally able to meet Cuba’s Fidel Castro on Sunday after holding a mass at Havana’s Revolution Square, which was previously reported by HNGN.

Francis is the third pope to visit the communist country in 17 years.

Current President and atheist Raul Castro welcomed the pope and has expressed hope Francis will speak out against Washington’s economic embargo against Cuba before leaving for the United States capital. In return, Castro gave Francis an interview book titled “Fidel and Religion”, written in 1985 by Freitas Betto.

Wearing a white button-down shirt and an Adidas track jacket, Cuba’s leftist icon and former leader, Fidel Castro, shook the hand of Pope Francis, the first pope from Latin America in Castro’s home in Havana, Cuba.

A priest places a skullcap on Pope Francis during Mass at Revolution Plaza in Havana, Cuba, Sunday September 20, 2015.

The pope later spoke at a vespers celebration at Havana Cathedral in which he warned against letting riches rule your life and called poverty “the wall and the mother of consecrated life”. Today, few Cubans regularly attend mass. John Paul II’s visit in 1998 was the first visit by a pope to Cuba since the revolution.

Pope Francis travels Tuesday from Cuba to the United States, trading the warm welcome he received on the communist island for a slightly chillier reception – at least in some quarters – from its old Cold War foe.