[Campion]

To be extremely picky, Peter wasn't crucified or buried "in Rome itself" -- the Vatican hill was outside the city limits at that time.

[Romulus]

The non-canonical Acts of Peter and Acts of Peter and Paul also are quite early and locate both apostles in Rome at the time of their martyrdoms. Ancient traditions, such as the crucifixion of Peter and the "Domine quo vadis" incident appear here as well. Consistent with historiographical standards and practices of their day, these documents are surely entitled to a respectful reading.