Antioch on the Orontes (/ˈænti.ɒk/ ; Ancient Greek: Ἀντιόχεια ἡ ἐπὶ Ὀρόντου, romanized: Antiókheia hē epì Oróntou, pronounced [anti.ó.kʰeː.a]) was a Hellenistic Greek city founded by Seleucus I Nicator in 300 BC. One of the most important Greek cities of the Hellenistic period, it served as the capital of the Seleucid Empire and later as regional capital to both the Roman and Byzantine Empire. During the Crusades, Antioch served as the capital of the Principality of Antioch, one of four Crusader states that were founded in the Levant. Its inhabitants were known as Antiochenes. The remains of the ancient city of Antioch are mostly buried beneath alluvial deposits from the Orontes River. The modern city of Antakya, in Hatay Province of Turkey, lies in its place.
Antioch was founded near the end of the 4th century BC by Seleucus I Nicator, one of Alexander the Great's generals, as one of the tetrapoleis of Seleucis of Syria. Seleucus encouraged Greeks from all over the Mediterranean to settle in the city. The city's location offered geographical, military, and economic benefits to its occupants; Antioch was heavily involved in the spice trade and lay within close reach of the Silk Road and the Royal Road. The city was the capital of the Seleucid Empire from 240 BC until 63 BC, when the Romans took control, making it the capital of the province of Syria and later of Coele Syria. During the late Hellenistic and Roman Principate periods, Antioch's population may have reached a peak of over 500,000 inhabitants (most generally estimate between 200,000 and 250,000), making the city the third largest in the Roman Empire after Rome and Alexandria and one of the most important cities in the eastern Mediterranean. From the early 4th century, Antioch was the seat of the comes Orientis, head of the Diocese of the East. The Romans provided the city with walls that encompassed almost 450 hectares (1,100 acres).