Seleucia Pieria was a town in antiquity, the capital of Seleucus I Nicator, in Syria Prima. It was the port of the western Seleucid capital of Antioch, lying close to the mouth of the Orontes. Its ruins lie near the modern town of Samandag in the Hatay province of Turkey. Seleucia, Apamea, Laodicea, and Antioch formed the Syrian tetrapolis.
According to Pausanias and Malalas, there appears to have been a previous city here named Palaeopolis ("Old City").
Seleucia Pieria was built by Seleucus I Nicator in ca. 300 BC. It lay near the mouth of the Orontes not far from Mount Casius, and functioned as the commercial and naval seaport of Antioch on the Orontes (now Antakya). The first colonists were the Greeks of Antigonia and some Jews. Seleucia was of great importance in the struggle between the Seleucids and the Ptolemies; it was captured by Ptolemy Euergetes in 246. The Lagids and Seleucids fought over the city and it changed hands several times until 219 BC when the Seleucid Antiochus III the Great captured it. Then it obtained its freedom and kept it even to the end of the Roman occupation; it had long enjoyed the right of coinage.
As the port of Antioch, "Seleucia on sea" - (so called to distinguish it from other cities of the same name) - is most notable as the precise point of embarkation from which the Apostle, St Paul, [in AD45] set forth on the first of his great missionary journeys, as chronicled in the Bible .
Famous residents included Apollophanes, a physician of Antiochus I Soter (third century BC), and Firmus who aroused Palmyra and Egypt against Rome in 272 AD.
Seleucia became a city of great importance, and was made a "free city" by Pompey. The harbour was enlarged several times under Diocletian and Constantius.
From the 5th to the 10th century, little is known of its history.
The Byzantines occupied the city from 970, followed soon after by the Frankish occupation, during which Seleucia regained its importance; during the Crusades its port was known by the name of Saint Symeon.
Paul of Tarsus and Saint Barnabas sailed from this port on their first missionary journey . The city was Christianized early. The oldest bishop known is Zenobius, present at the Council of Nicaea in 325. Other known bishops include Eusebius, an Arian, and Bizus in the fourth century, with twelve others cited by Le Quien . In the sixth century the Notitia Episcopatuum of Antioch, gives Seleucia Pieria as an autocephalous archbishopric, suffragan of Antioch ; the diocese existed until the tenth century, and its boundaries are known . For some Roman Catholic titularies see Eubel, Hierarchia catholica medii aevi, I, 468.
The city is still a titular see of the Roman Catholic Church, Seleuciensis Pierius; the seat is vacant following the death of the last bishop in 1980.
The upper city, about 13 km in circumference, is still distinguishable. The lower city, smaller than the preceding one, was more thickly populated. Among the curiosities are a necropolis of little interest, some irrigation works, and some fortifications very much damaged. Considerable remains are still visible: the chief are those of a cutting through the solid rock nearly 1100 yds. long, which Polybius describes as the road from the city to the sea; the triple line of walls; amphitheatre, cemetery, citadel, temples.