As another "study break" last week I went to the Mamertime prison with a friend. The "Mamertinum" is the ancient prision down by the Roman Forum, dating from many years before Christ, that was used to hold both St. Peter and St. Paul - the pillar that they were chained to is still preserved. It has been basically made into a little chapel / tourist attraction (unfortunately, a common occurance here in Rome...). There is a church built on top of it also of interest, dedicated to St. Joseph the Worker - there are almost no churches here in Rome dedicated to Joseph, for some reason devotion to him started really late.