The original name of the city of Thessalonica was Therma, or Therme, meaning “hot bath” or “hot springs” due to the warm salt-springs nearby. A king of Macedonia named Cassander rebuilt and renamed the city in 315 BC after his wife Thessalonike, who was also sister to Alexander the Great.
The city’s harbor was Macedonia’s chief naval station until it was taken by the Romans in 168 BC. At that time, the Romans made Thessalonica the capital of one of the districts of Macedonia. Afterward, four districts of Macedonia became one province under the rule of a proconsul who lived in Macedonia. Like those before Rome’s rule, the city was an important naval base for their fleet. Other important Roman bases included Corinth in Greece and Ephesus, located across the Aegean.
The city, also, shared the trade between the east and west with Corinth because the cargo ported in either place. From Thessalonica, the goods were loaded onto wagons traveling west across Greece on the famous Egnatian Way. Although this highway was built by Rome to allow easy and quick for the military to access regions of the empire, it was an important trade route that ran through Thessalonica. Being such an important city, it was home to many Hellenistic Jews and Gentiles.
In reference to Paul, he and his companions sailed to Macedonia (Acts 16:6-ff) and walked to Philippi, where they merged onto the Egnatian Way, passing through Amphipolis and Apollonia before reaching Thessalonica. While there, they taught in the local synagogue for three straight Sabbaths. That’s his connection to Thessalonica. As a result of an uproar, Paul and Silas left for Berea. Paul went on to Athens and Corinth. While in Corinth, it is believed that Paul wrote both letters to the saints in Thessalonica in the early 50s.