Why Did St. Irenaeus say the Church was Founded and Organized in Rome by Peter and Paul?

In c. A.D. 189, St. Irenaeus wrote: > Since, however, it would be very tedious . . . to reckon up the successions of all the churches, we put to confusion all those who, in whatever manner, whether by an evil self-pleasing, by vanity, or by blindness and perverse opinion, assemble in unauthorized meetings, by indicating that Tradition derived from the apostles, of the very great, the very ancient, and **universally known Church founded and organized at Rome by the two most glorious apostles, Peter and Paul**; also [by pointing out] the faith preached to men, which comes down to our time by means of the successions of the bishops. For it is a matter of necessity that every church agree with this Church, on account of its preeminent authority, that is, the faithful everywhere, because the apostolic Tradition has been preserved continuously by those [faithful men] who exist everywhere [*Against Heresies* 3:3:2] Why did St. Irenaeus say the Church was founded and organized in Rome by Peter and Paul? I'd understand if he was speaking of the lowercase 'c' church in Rome, but he spoke of "the very great, the very ancient, and universally known Church," so—correct me if I'm wrong—he was speaking of the entire Church rather than the singular church in Rome. So what does he mean exactly?