Question: What are the four greater or patriarchal basilicas of Rome? They represent the four great ecclesiastical provinces of the world.
Answer:
St. Peter's is assigned to the Patriarch of Constantinople,
St. Paul's to the Patriarch of Alexandria,
St. Mary Major to the Patriarch of Antioch.
St. Lawrence-outside-the-Walls is also reckoned as a greater basilica because it is specially attributed to the Patriarch of Jerusalem.
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http://www.newadvent.org/cathen/02325a.htm
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https://www.youtube.com/watch?v=vcyWR1jKBw8