Pope Francis told hundreds of children from the poorer neighborhoods of Rome and Milan never to forget their first teachers, in the latest edition of the Treno dei Bambini – the children’s train – on Saturday.

The first Treno dei Bambini arrived at the Vatican’s train station in 2013, under the patronage of the Courtyard of the Gentiles, a dialogue project of the Vatican’s Council for Culture.

Since then, the train has brought underprivileged children from different parts of Italy for a meeting with the pope.

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This year, more than 500 children took the sixth edition of the trip, which has as its theme “Friendly City.”

It is part of a project to redevelop dilapidated areas of cities where children often face bleak prospects.

“Never forget the first teachers, never forget the school, because they are the roots of your culture. And remembering your teachers and your schools will help you not to be uprooted, and help you bear flowers and fruits,” Francis said, according to Vatican News, a service of the Vatican’s Secretariat for Communication.

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The pope spoke to the children about Stella, a teacher who taught the young Jorge Bergoglio in first and second grades. Francis said he kept in contact with her and was close to her even when he was a bishop in Buenos Aires, when she died at the age of 94.

“I always kept up with her. I never forgot her,” Francis said.

He told the children the Argentine capital was the “most beautiful city in the world,” and that “in my neighborhood [the historic Flores district], there was a beautiful square to play soccer.”

He said that the neighborhood children also enjoyed kite flying and held a championship for “the one most beautifully decorated and the one that went highest.”

Francis reminisced about the Carnival season – Mardi Gras – and how the children wore costumes during the parade.

“We went through the streets singing and even ringing doorbells, asking for something with which to buy chocolates,” he said.

The children gave the pontiff handmade gifts, which Francis said he appreciated because “it is important because you have done it with intelligence, with your hands and with your heart.”

“And when something is done with intelligence, with the heart and with the hands, it is a profound and human thing,” the pope said.