Antioch was at one time the third-largest city in the Roman Empire, after Alexandria in Egypt, and Rome itself. There were a number of other cities by the same name, so this Antioch was known as Antioch on the Orontes (i.e. the Orontes River, along which it was located), or Antioch of Syria (or Syrian Antioch), to distinguish it from, for example, Pisidian Antioch which was located to the north in what is today Turkey.
Antioch is believed to have been founded by Seleucus Nicator around 300 B.C. It was a busy maritime city from early on, about 20 miles from the Mediterranean Sea up the Orontes River. It was also on a natural route to Jerusalem, 300 miles to the south. See also Roman Roads.
Antioch was a important in the early spread of Christianity - the fact that the term "Christian" originated there attests well to that. It was also a safe haven for believers who fled from Jerusalem after the persecution that broke out after the stoning of Stephen - considered to be the first Christian martyr.
After his conversion from Saul, Paul was often in Antioch, sometimes using it as a home base for his missionary travels - see Paul's First Missionary Journey, Paul's Second Missionary Journey and Paul's Third Missionary Journey.
It was at Antioch that Paul (a man with a rather intense personality), publicly disagreed with Peter (a man with an equally intense personality) regarding the acceptance of Gentiles (Galatians 2:11,14). The incident was remarkable for 2 reasons. First, it shows that the saints were just as "human" as anyone today (see What Is A Saint?), and second, it casts a great deal of doubt upon the doctrine of "the primacy of Peter." Peter was most certainly a very important element in the early Christian church, but he was one of many key individuals, none of whom, including Peter, ever attempted to exercise authority over all of the others who had received the same calling.
Fact Finder: Did the church at Antioch have both Jews and Gentiles (Greeks)?