St. Peter's Basilica is one of the Papal Basilicas (previously styled "patriarchal basilicas")[REF] and one of the four Major Basilicas of Rome, the other Major Basilicas (all of which are also Papal Basilicas) being the Basilicas of St. John Lateran, St. Mary Major, and St. Paul outside the Walls.
As one of the constituent structures of the historically and architecturally significant Vatican City, St. Peter's Basilica was inscribed as a UNESCO World Heritage Site in 1984 under criteria (i), (ii), (iv), and (vi) [REF].