Pope Francis was delivering a homily but a little boy stole the show.

Pope Francis let the boy explore the area undisturbed before tens of thousands of people. (L'Osservatore Romano/Associated Press)

Francis was speaking in St. Peter's Square about the important role grandparents play when a little boy walked up behind him and confidently climbed up and sat down on the pontiff's white chair.

The Vatican says Francis was surrounded by elderly faithful and their grandchildren Saturday night at a rally to encourage family life when the boy came up, wearing a striped shirt, jeans and sneakers.

Francis let the boy explore the area undisturbed before tens of thousands of people. The pope smiled while reading his speech as the boy sat in the empty chair, gazed up at him and even at one point clung to the pontiff's legs.