Got a quick question for you. Do we know who started up the congregation in Rome? Of course we know that it wasn't Paul by the way he words his epistle to them, but wondered just who did. or if we even know.
The quick answer is, no, we have no idea. Unlike many of the other churches to whom Paul wrote, Paul did not have a hand in starting this particular work. The church there had a good reputation (Romans 1:8) and was in existence for a number of years before Paul wrote to them (Romans 15:23).
The church is mostly composed of Gentile people (Romans 1:13; 11:13), but there were those who had converted from Judaism there as well (Romans 2:17-23; 7:1). Philo mentioned that there were many Jews in Rome, brought there from earlier battles. Most were no longer slaves because “being made captive in war, and brought into Italy, they were set at liberty by their masters, neither were they compelled to change the rites of their fathers” [Philo, Leta. Ad Caium]. The church in Rome appears to have been a large congregation because Tacitus, a Roman historian, referred to the Christians in A.D. 64, during Nero’s persecution, as being “an immense multitude” [Annals 15.44].