Amphipolis was a Roman military post on the Egnatian Way in northeastern Macedonia.
Apollonia, named after the Greek god Apollo, was also on the Egnatian Way.
Thessalonica was a good place to begin ministry because it had a Jewish synagogue (see study note on 9:2). Paul preached there for three consecutive Sabbath days. He explained the Scriptures and showed how they are fulfilled in Jesus (how they come true in him).