On his arrival, he greeted the people from the balcony of Villa Barberini on the grounds of the papal summer residence, where he will be staying until 20 July.
"I hope that I can use this time to strengthen my body and mind," he said before setting off on Sunday from St Peter's Square.
According to a friend, the head of the Augustinian order, the Pope wants to use the time to write his first encyclical. A title is not yet known.
"He only told me the other day that he would use these two weeks to work out the basic structure of the text," said Prior General Alejandro Moral in an interview with the Italian daily newspaper "Il Messaggero" (Sunday).
He surmises that the topics of peace, social teaching, unity and artificial intelligence (AI) could play a role in the papal doctrinal letter.
Audiences suspended
During the summer break, all public and private papal audiences will be suspended. On the two Sundays of his stay, Leo intends to say his usual midday prayers in the square in front of the papal palace.
Masses are also planned in the parish of San Tommaso da Villanova in Castel Gandolfo (13 July) and in Albano Cathedral (20 July).
Since Urban VIII (1623-1644), most popes have taken a few weeks off from hot Rome in the summer residence in the Alban Hills in July and August.
Most recently, John Paul II (1978-2005) and Benedict XVI (2005-2013) repeatedly retreated to the complex at an altitude of 426 metres.
Pope Francis broke with this tradition and remained in the Vatican in the summer, merely reducing his workload.