He was in Babylon according to 1 Peter 5:13 where he wrote this first epistle circa 65 AD. It was not even part of the Roman Empire then, but part of the Parthian Empire with a substantial Jewish population centering around the Babylonian Talmud.
I have to ask, Why do you not want it to be true that Peter was in Rome? It seems to me that you desparately don't want to acknowledge that Peter was in Rome. That you just made up the notion that Luke claimed Peter was imprisoned by Herod in 44 AD, apparently in order to attempt to refute Jerome, is telling. Why do you kick against the goads?
-A8