Philippi was a Roman colony located approximately 10 miles northwest of the seaport of Neopolis. The cities’ population during Paul’s time was about 40,000. Paul would have walked on the Via Egnatia (or Egnatia Way) to Philippi.
The emperor organized areas into colonies. Certain places were selected for Roman citizens (especially retired military people) to live in. This gave them a strong pro-Roman influence in these strategic areas. Philippi had been a Roman colony since 42 BC. The citizens of Philippi were expected to be loyal to Rome even though they were living on foreign soil. They were to obey the laws of Rome and expected to give honor to the Roman emperor. In return for their loyalty they were exempt from taxes and given certain political privileges.
The Forum or marketplace, was an essential part of a Greek city-state. It was a large, open, rectangular space in the central part of a city which acted as a common place of assembly of the people.