Each November 9, the Church celebrates the feast of the Dedication of the Lateran Basilica in Rome, the oldest and highest ranking of the four major basilicas in Rome. The Basilica of St. John Lateran is the cathedral of the diocese of Rome, the official ecclesiastical seat of the Holy Father, the Bishop of Rome, not St. Peter's Basilica as so many mistakenly believe. The Basilica is also called the Church of Holy Savior or the Church of St. John Baptist.
In ancient Rome this was the church where everyone was baptized. It the oldest church in the West, built in the time of Constantine and was consecrated by Pope Sylvester in 324. This feast became a universal celebration in honor of the archbasilica, the ecclesiastical mother church, called "the mother and mistress of all churches of Rome and the world" (omnium urbis et orbis ecclesiarum mater et caput), as a sign of love for and union with the See of Peter.
The Archbasilica has two co-patrons, just like our cathedral in Providence has two, St. Peter and St. Paul. In this case, the co-patrons are both named John. They are St. John the Baptist and St. John the Evangelist. The second part of the name, Lateran, refers to the Laterani family who originally owned the property and the palace that was there when it was given to Pope Miltiades and the Church by the Emperor Constantine around the year 313 AD. Pope Sylvester I, who dedicated the newly constructed basilica in 324 AD made it his cathedral as Bishop of Rome and took up residence in the palace adjacent to the church.
Initially the observance of this feast was confined to the city of Rome; then, beginning in 1565, it was extended to all the Churches of the Roman rite. The honoring of this sacred edifice was a way of expressing love and veneration for the Roman Church, which, as St. Ignatius of Antioch says, “presides in charity” over the whole Catholic communion (Letter to the Romans, 1:1).
St. John Lateran was the home of the popes—the center of the Catholic world for many years. Twenty-eight popes are buried there. Although our pope now lives at the Vatican and presides at St. Peter’s basilica, St. John Lateran is considered his cathedral as the bishop of Rome. The dedication of this basilica is a happy occasion for the Church because it reminds us of our beginnings, our unity. It stands as a monument to God and all that God does through the Church.
Today’s feast celebrates a mystery that is always relevant: God’s desire to build a spiritual temple in the world, a community that worships him in spirit and truth (cf. John 4:23-24). But this observance also reminds us of the importance of the material buildings in which the community gathers to celebrate the praises of God. Every community therefore has the duty to take special care of its own sacred buildings, which are a precious religious and historical patrimony. For this we call upon the intercession of Mary Most Holy, that she help us to become, like her, the “house of God,” living temple of his love. Benedict XVI, Angelus Address, November 9, 2008