There's a lot going on in the church and the neighboring religious complex, far too much to bore you with here (although if I had a photo of the silver jars on the altar containing the heads of Saints Peter and Paul I would have included that as a conversation piece). I do have a photo of the original bronze doors to the ancient Roman Senate, which the church thought would look better here. The lovely columned cloisters surrounding a pretty garden are definitely the nicest part of the cathedral, and surprisingly rare in Rome.

The square in front of the church is a bit scruffy, but if you can make out a dark brick building in the photo, that's the first baptistery in Christianity, built by emperor Constantine around 320. It became the template for all the other baptisteries in Italy, although future generations had the good sense to decorate the exterior. Next to it is part of the Lateran Palace, the popes' main home until the move to the Vatican. The only part of the palace that is a bit open to visitors is the Santa Scala, the staircase with the kneeling pilgrims crawling up it. If you're a believer, this staircase was brought here from Pontius Pilate's palace in Jerusalem, where Jesus walked after being sentenced to death. If you choose to see it, you have to walk up on your knees, although famously Martin Luther was doing that when half way up the stairs he heard a voice telling him that "the just shall live by faith, not by pilgrimage", whereupon he scandalously stood up and walked down the steps. At the top of the steps, and definitely not open to the public, is the pope's private chapel, which, as the name implies, is only accessible to popes. Inside is a portrait of Jesus painted by angels, so I'm guessing the church could raise a lot of money if they charged admission to see it.