The Chicago-born pope said that a gathering of young faithfuls in Rome was a "sign that a different world is possible."

The Vatican estimates that more than one million young people from 146 countries gathered for Pope Leo’s largest mass since he was elected in May. In his homily, the Pope gave an encouraging message of hope to young crowd.

Pope Leo celebrated the largest event yet of his nearly three-month tenure on Sunday, encouraging a crowd of more than a million Catholic young people gathered in a field on the outskirts of Rome to spread their faith.