There's a list of the 4 papal these churches, which in addition to St. Peter's include St. John Lateran
Thus, while of the Major Basilicas, the Basilica of St. Peter's alone is 
within... [DOC] [TLE] The organization of the Roman Catholic church - Bible.ca [PAR] There is only one bishop for each of these "diocese head" mother churches ... 
You will notice that even the local church of St. John Lateran Basilica (Rome 
diocese) ... Notice that the Pope actually holds three positions in the Catholic 
church: 1.