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The four major basilicas in the Roman Catholic Church:
More Information Official site
A wealthy but childless Christian Roman couple wanted to appoint the Virgin Mary as heiress of their property. On the night of August 4, Mary appeared simultaneously to the couple and Pope Liberius, expressing the wish that a church be erected on Esquiline Hill. The morning of August 5, miraculous snow fell on a narrow piece of land, upon which the Church of Liberius was constructed. This Marian shrine was replaced in the fifth century with a great church named Santa Maria Maggiore, which is now one of the four major basilicas....
Possibly the most famous church in the world, and one of the four papal basilicas, the current building was built between 1506 and 1626, replacing the original from the time of Constantine in the 4th century. St. Peter’s tomb lies beneath the high altar of the basilica, and the church continues to be a place of interment for popes, cardinals and bishops. More Information Official site