Philippopolis was founded as a "polis" by Philip the Great (), the king of ancient Macedonia, settling there both Thracians and 2,000 Macedonians and Greeks in 342 BCE. Control of the city alternated between the Macedonian kingdom and the Thracian Odrysian kingdom during the Hellenistic period; the Macedonian king Philip V () reoccupied the city in 183 BCE and his successor Perseus () held the city with the Odrysians until the Roman Republic conquered the Macedonian kingdom in 168 BC. Philippopolis became the capital of the Roman province of Thracia. The city was at the centre of the road network of inland Thrace, and the strategic "Via Militaris" was crossed by several other roads at the site, leading to the Danube, the Aegean Sea, and the Black Sea. The Roman emperor Marcus Aurelius () built a new wall around the city.