San Giovanni in Laterano Rome
It may come as a surprise to learn that San Giovanni, not St. Peter's, is the official cathedral of the diocese of Rome and therefore the mother of all Catholic churches. It is here that the Pope celebrates Mass on the churches holiest days. This was Christendom's first cathedral, built by Constantine in the 4th century. Destroyed by fire several times, the building bears little resemblance to the first structure that stood on this site. Only portions of the baptistry are original.

The heads of both St. Peter and St. Paul are kept in the tabernacle above the altar. The steps across the street are allegedly the same ones that Christ climbed to face judgment before Pontius Pilate. Pilgrims come from all over the world to scale these steps on their knees and worship. The place next to the church, Palazzo Laterano was home to the popes until the 14th century.