The proud capital of the Roman province of Macedonia with a population of over 100,000. Its natural harbor and placement on the east-west Egnatian Way as well as key north-south trade routes made it a flourishing center of trade and philosophy. It was a free city, governed by local officials called "politarchs." The people were devoted to the Greco-Roman pantheon and the imperial cult. Egyptian cults were also prominent, and there was a sizable population of Jews as illustrated in Acts 17:5.
(The ESV Study BibleTM, English Standard Version (ESV) by Crossway Bibles, 2007. Page 2301)