[bboop]

The Romans brought ordered life/ roads/ trade to a huge swath of Europe. When Constantine legalized Christianity in the Roman Empire in 313, Western Civ was born.

I vote for the Romans.

[ARepublicanForAllReasons]

I've got to go with the Romans also, since the (so-called) Barbarians adopted it, in time. Although things were legally a mess in Europe before Charlemagne, because each Germanic tribe demanded to be judged under its own laws.

FYI, bboop, Constantine didn't legalize Christianity, he just made it the official religion of the Roman Empire. Christianity was persecuted, then tolerated, then persecuted, back and forth up until that time, by the Roman authorities. Most of the time, they were left alone as long as they didn't preach against the Emperor, like St. Sebastian.

Also, Julian the Apostate (ruled just 19 months 331-332 AD) tried to re-introduce the gods of Roman and Greek mythology, but had a bad accident (likely shot by one of his own soldiers) during a battle in Persia. Sort of like what happened to Caligula, who also outraged the Roman aristocracy.