Pope Leo XIV’s inauguration Mass on Sunday morning at St. Peter’s Square is an ancient ritual filled with symbolism that connects back to Peter, Jesus’ apostle, and his special mission as head of the Catholic Church.

Leo XIV, the first ever American pope, will be formally inaugurated as the 267th pontiff Sunday during a special Mass in St. Peter’s Square attended by world leaders, royalty, and thousands of believers.

Pope Leo XIV has taken the reins as leader of the Catholic Church, and on Friday, May 9, started his first full day as Pontiff with a mass at the Sistine Chapel, during which he called his election both a cross and a blessing.