Philippi, an important early center of Christianity, was founded as a Roman colony and named after the father of Alexander the Great. It was at the city a woman named Lydia (and her family) converted to Christianity after hearing Paul’s teaching, and convinced the Apostle to stay with her. After Paul cast a demon out of a fortune-telling slave girl he was put in the city’s prison. While Paul and Silas were praying and singing in the jail there was an earthquake, freeing the men. After Paul convinced the jailer not to kill himself, the jailer also converted (Acts 16:11-34). These believers grew into a church, and by the time of Paul’s letter to them, he praised them for their assistance to his ministry. The city itself prospered until the seventh century, when attacks from Slavic raiders and several severe earthquakes put the city into a long gradual decline. The area remained largely abandoned until the new town of Krinides was built nearby in the twentieth century.

Philippi was excavated beginning in 1917 by the French School of Archaeology at Athens. They uncovered a Roman era agora, built on top of an older market that was likely the “marketplace” Silas and Paul were dragged to before being imprisoned.   They also found the ruins of a fourth-century church dedicated to Paul, and another large fourth-century church just outside the city. 

They also uncovered a structure popularly thought to be the prison Paul and Silas were put in. However, the area was not a prison but a complex of religious buildings first erected in the Hellenistic period. Prisons were not built in a religious complex. Nevertheless, frescoes and a small chapel were found in it, leading to the idea that it was the site of Paul’s imprisonment.

Randall Price and H. Wayne House, Zondervan Handbook of Biblical Archaeology (Grand Rapids, Mich. 2017), 314-316.