Philippi was a city in eastern Macedonia established by King Philip II of Macedon. The king started the city in 356 B.C., the same year his son and heir to the throne Alexander III (also known as Alexander the Great) was born. The objective of founding the town was to take control of the neighboring gold mines and to establish a garrison at a strategic passage.
During his second missionary journey Paul, in Troas, sees a vision of a man in Macedonia (Greece) asking for help (Acts 16:8-9). Paul, Silas and others immediately set sail for Neapolis. From Neapolis they travel to Philippi.
While in Philippi Paul casts a demon out of a female slave (Acts 16:16-18). Her masters, however, angry that they have lost the ability to make more money off of their fortune telling slave, stir up the city against Paul and Silas. The two evangelists are arrested, beaten and put in prison. Paul, Silas and others are freed when a miraculous earthquake causes ALL the cell doors to open and the bonds of ALL prisoners to be loosed! This miracle leads to the conversion of not only the prison jailor but his entire family:
"But at midnight Paul and Silas were praying and singing hymns to God, and the prisoners were listening to them. Suddenly there was a great earthquake, so that the foundations of the prison were shaken; and immediately all the doors were opened and everyone’s chains were loosed.
"And the keeper of the prison, awaking from sleep and seeing the prison doors open, supposing the prisoners had fled, drew his sword and was about to kill himself. But Paul called with a loud voice, saying, 'Do yourself no harm, for we are all here.'
"Then he called for a light, ran in, and fell down trembling before Paul and Silas. And he brought them out and said, 'Sirs, what must I do to be saved?' So they said, 'Believe on the Lord Jesus Christ, and you will be saved, you and your household.'
"Then they spoke the word of the Lord to him and to all who were in his house. And he took them the same hour of the night and washed their stripes. And immediately he and all his family were baptized. " (Acts 16:25-33, NKJV)