What is the Highest Ranking Church in Catholicism, the Ecumenical Mother Church?

Here's a clue: It's not St. Peter's Basilica. The giant Basilica designed by Michelangelo and others throughout the centuries, and completed in the 16th, known as St. Peter's Basilica, which can be seen in St. Peter's Square, and is by far the most well-known basilica in the world, is amazingly, not the highest ranking church in the Catholic Church. It is in fact the Basilica of St. John Lateran.

St. John Lateran Basilica is the cathedral church of Rome and the official ecclesiastical seat of the Pope. Officially named Archibasilica Sanctissimi Salvatoris (Archbasilica of the Most Holy Savior), it is the oldest and ranks first (being the only cathedral in Rome) among the four major basilicas of Rome, and holds the title of ecumenical mother church (mother church of the whole inhabited world) among Catholics.

This very beautiful cathedral has a very amazing history. The place where the cathedral is now located, was once used by Roman emperors, and was given, as a gift, to the Bishop of Rome (the Pope), by Emperor Constantine, when Christianity was legalized and became the official religion of the Roman empire.

The official dedication of the Basilica and the adjacent Lateran Palace was presided over by Pope Sylvester I in 324, declaring both to be Domus Dei or "House of God." In its interior, the Papal Throne was placed, making it the Cathedral of the Bishop of Rome. In reflection of the basilica's primacy in the world as mother church, the words Sacrosancta Lateranensis ecclesia omnium urbis et orbis ecclesiarum mater et caput are incised in the main door, meaning "Most Holy Lateran Church, of all the churches in the city and the world, the mother and head."

The Lateran Palace and basilica have been rededicated twice. Pope Sergius III dedicated them to Saint John the Baptist in the 10th century in honor of the newly consecrated baptistry of the Basilica. Pope Lucius II dedicated the Lateran Palace and basilica to Saint John the Evangelist in the 12th century. However, St. John Baptist and St. John the Evangelist are regarded as co-patrons of the Cathedral, the chief patron being Christ the Saviour himself, as the inscription in the entrance of the Basilica indicates, and as is tradition in the Patriachal Cathedrals. Thus, the Basilica remains dedicated to the Saviour. That is why sometimes the Basilica will be referred to by the full title of Archabsilica of the Most Holy Saviour and of Sts. John Baptist and John Evangelist in the Lateran.

Next time you're in Rome, make sure to visit the Basilica of St. John Lateran.