The Church had reached Rome even before Peter (the Church's designated head) and Paul (its chief missionary) took residence there. IN the year 41, eight years after the Resurrection and before Paul ever began his mission, there were enough Christians in Rome to start major riots with the local Jews, which forced the then emperor Claudius to expel both. This is stated by the historian Suetonius (who, not understanding the Jewish term Christus, the Anointed One - since anointing was not a sign of coronation among the Greeks and Romans - misread His name as Chrestus, a common slave's name) and confirmed by Acts, in which Luke testifies that, when in Corinth, Paul was the guest of two rich Roman Christian Jews who had the Roman names Aquila and Priscilla. They had been expelled from Rome by Claudius. So, before written record begins, there was a solid Roman Christian community among the local Jews, speaking Latin. This is shown not only by the names of Aquila and Priscilla, but by the fact that they settled in Corinth - the only city in Greece which spoke Latin rather than Greek. Early testimony is unanimous that Peter settled in Rome, became the leader of the local Church, was murdered by Nero in 64, and his tomb has been found exactly below the great altar at St.Peter's. What more evidence do you want? And who else except Peter did Jesus put at the head of his Ekklesia?