Catholic cardinals gathered at the Vatican this week to elect the successor to Pope Francis, who died on April 21.

Robert Prevost, who took the name Pope Leo XIV, led his first Mass at the Sistine Chapel. He is the first American pope in Catholic church history.

A formal Mass to mark the inauguration of Pope Leo XIV will take place on May 18 in St. Peter's Square, the Vatican announced the day after stunning the world with the election of the first pope from the United States in the Church's history.