Philippi was founded by settlers from the Greek island of Thassos in approximately 360 BC. A few years after its founding, the city was captured by Philip II, the Macedonian king and father of Alexander the Great. In 168 BC, the Roman Republic defeated the Antigonid Kingdom in the Third Macedonia War and took control of cities like Philippi.
During the flashpoints surrounding the murder of Julius Caesar and the ensuing civil war, Philippi became the site of one of the most pivotal battles in Roman history. Octavian and Marc Anthony, Caesar's loyal successors, triumphed over their rivals Brutus and Cassius just outside the city.
After Octavian became the first emperor Augustus in 27 BC, Philippi experienced an influx of Roman veterans and settlers. Philippi was one of the major cities located on the Via Egnatia, a vital road that linked Rome's Greek and Balkan territories to the rest of the empire. It was also strategically important because of its gold mines. Although some Romanization took place, most of the Macedonian city was left untouched.
A forum was built on either side of the main road, not far from a Greek agora that had been the center of the Macedonian city. Construction on the forum started under the reign of the emperor Claudius and continued in various forms until the middle of the 1st Century AD.
Philippi remained a part of various empires for centuries, including the Byzantines, until it was later abandoned. It was also one of the earlier Christian centers of the later Roman empire.