Each year for the Feast of Corpus Christi, the Pope, the Bishop of Rome celebrates Mass in the City’s Cathedral, the Archbasilica of Saint John Lateran. 
Immediately following the Mass, the Holy Father will process with the Blessed Sacrament from the Lateran to the Basilica of St. Mary Major.

Parishes, confraternities and other groups of the faithful take part in Procession, which was revived during the Pontificate of Blessed John Paul II. 
“All the external symbols that we have in the procession for the Blessed Eucharist come from the ancient world, and they were symbols, things used to honour aperson,” said Father Joseph Kramer, the Pastor of Santissima Trinità dei Pellegrini in Rome. “And I think that’s the big message of the procession, that this is a VIP holding up the traffic today, moving from one point in Rome to another . . . the fact that the Pope is the first person that’s following the monstrance, gives you an indication that here we’ve got Somebody more important than the Pope in Rome, and that’s our Lord Himself Who’s being carried in procession.”
Father Kramer spoke about the composition of the procession: “All the parishes go, every parish goes with a group of laity. The parish priests all go, and all wear their stoles, and form a great block of the clergy. And then the confraternities are present. There are lots of confraternities in Rome,” he explained, “all very venerable institutions, going back hundreds of years, and they wear their distinctive habits and form part of this great procession.”
The procession, said Father Kramer, fills the Via Merulana that stretches between the two papal Basilicas. “When the first people arrive at St. Mary Major’s, some people are still leaving the Basilica of the Lateran, so that shows you how many people are involved. And then other people line the streets behind the barricade, watching the whole thing. So it’s a big event, it’s thousands of people.”
Father Kramer pointed to the symbolism of procession: “I think the symbolism of walking behind the Blessed Sacrament is rather beautiful, because it means you want to walk in the ways of the Lord, you want to follow Him in everything. It’s a symbolic way of saying ‘In my life I’m following Christ’.”