@Cristian022 do we have any record of any apostle going to the literal city of Babylon? No? I think the best answer here is Rome, as some of my brothers have already said.
@Cristian022 these are good questions we need to be asking. I do not see Peter as associating Rome (in this case as a heathen city) with the future prophetic Babylon of Armageddon. I think that is an unnecessary assumption
In short, it doesn't make sense for Peter to give a very abrupt prophetic association in his farewell remarks.