Filyos Tios Archaeological Site is a multi-layered ancient settlement located in the town of Filyos, within the Çaycuma district of Zonguldak Province, on the Black Sea coast. Known by various names such as Tios, Tieion, and Tium in antiquity, the city was colonized in the second half of the 7th century BC by Milesians under the leadership of a priest named Tios. Its location—positioned on an important transit point between Western Paphlagonia and Eastern Bithynia—ensured that Tios fell under the rule of various kingdoms throughout history. In 70 BC, the city was incorporated into the Roman Empire and developed into an important political, economic, and religious center, particularly during the Roman and Byzantine periods.
In antiquity, Tios occupied a strategic position along both land and maritime trade routes. The transportation opportunities provided by the Billaios (Filyos) River enabled the export of products such as grain, fish, and wine from the hinterland via the city’s harbor to other parts of the Black Sea and beyond. Excavations at the site have revealed a rich architectural heritage, including fortress and defensive walls from the Roman and Byzantine periods, a theater, bathhouse, aqueduct, temple, nymphaeum, necropolis areas, and submerged pedestals. The fact that modern settlement developed outside the boundaries of the ancient city has allowed Tios to remain one of the best-preserved ancient sites along the Western Black Sea coast.
Filyos Tios Archaeological Site (Photo: T.C. Sanayi ve Teknoloji Bakanlığı, Kalkınma Galerisi)
History
In antiquity, the city was significant both strategically and commercially as it served as a transit point between Western Paphlagonia and Eastern Bithynia. According to Strabo, before Hellenic colonization, a native people known as the Kaukon inhabited the area. There are differing views regarding the origin of the Kaukon; some describe them as Scythian, while others consider them Macedonian or Pelasgian. Additionally, it is suggested that another people, known as the Bebryk, also lived in the region and were connected to the Phrygians.
The foundation of Tios is dated to the second half of the 7th century BC. According to Stephanos Byzantinos’s work Ethnika, the leader who founded the city was a Milesian priest named Tios, after whom the city was named. Another account states that a figure named Pataros, who led people from Thrace, captured the area and named it “Tios” in honor of Zeus. This second version supports an etymological interpretation that the city’s name is a derivative of Zeus’s name. In its early period, the city began minting its own coins under the rule of Herakleia Pontike; later, it was incorporated sequentially into the Amastris Synoikismos under Queen Amastris, the Kingdom of Bithynia, and the Kingdom of Pontus. During these transitions, Tios frequently changed hands, particularly between Bithynia and Pontus.
In 70 BC, the city was incorporated into Roman territory by the expedition of Roman General Aurelius Cotta and became part of the Pontus-Bithynia Province. During the Roman period, Tios experienced significant development, evolving into an important harbor and trade center. With its harbors and the transportation provided by the Billaios River, the export of wine, fish, and grain from the hinterland played a major role in the city’s economy. Renovations of roads and harbor infrastructure commissioned by imperial authorities are attested by milestone inscriptions. Epigraphic evidence from the Roman period indicates the presence of cults dedicated to Zeus, Helios, Dionysos, Asklepios, and the Great Goddess, shedding light on the city’s religious practices.
During the Byzantine period, Tios became a bishopric center, gaining regional religious importance. From the 6th century AD onwards, sources increasingly emphasize a Christian identity supported by religious structures and inscriptions. In 1261, the city came under Genoese control, and in the early 15th century, it was incorporated into Ottoman territories. In the Ottoman period, having lost its character as a harbor city, Tios transformed into a small fishing village and came to be known as “Filyos,” a name derived from the Billaios River located to the east of the ancient city.
In modern times, Filyos has largely developed outside the ancient city’s boundaries, which has helped preserve much of Tios’s architectural heritage. As a result, the site is one of the best-preserved ancient settlements along the Black Sea coast of Türkiye. Systematic archaeological excavations began in 2006 under the direction of Prof. Dr. Sümer Atasoy, and by 2007, excavations had been expanded to reveal the fortress walls, theater, bathhouse, nymphaeum, aqueduct, vaulted gallery, necropolises, and numerous smaller finds.
Architectural Remains
The Filyos Tios Archaeological Site is topographically divided into two main sections: the Upper City (Acropolis) and the Lower City. Spanning approximately 60 hectares, numerous architectural remains from various periods have been uncovered.
Acropolis (Fortress Hill)
This area contains the city’s earliest settlement layers. Here, fortress walls from the Hellenistic and Roman periods and the remains of a tower have been found. Additionally, a cistern with an underlying platform and rubble remnants have been detected. Surface surveys on the Eastern Hill have revealed grave steles, stone sarcophagi, and column fragments, suggesting that this area functioned as a necropolis.
Theater
Built on the southern slopes and adapted to the sloping terrain, the theater is one of the rare examples of a Roman-era theater that has survived on the Black Sea coast. Parts of the stone seating remain, and the stage area has been partially exposed through excavations. Two sculptural fragments were also recovered during the theater excavations.
Ancient Harbor and Pedestals
Located to the west of Fortress Hill, the ancient harbor area now lies partially submerged. Two pedestal remains—measuring 6 meters in width and extending over 100 meters—indicate the city’s historical commercial and military significance. The coastal wall extends from this harbor into the interior of the city, forming a protected structure approximately 1 meter thick and 5 meters high.
City Center (“Bahçe”)
Known locally as “Bahçe” (Garden), this area has revealed stone-paved roads, remains of a bathhouse, an aqueduct, a nymphaeum, a vaulted gallery, and various building foundations. Under the bathhouse, a hypocaust system has been documented, indicating that the structure was heated. Near the nymphaeum, numerous architectural fragments and ceramic finds have been recovered. The vaulted gallery, whose function is not yet fully determined, is colloquially known as the “underground city.”
Additional remains include necropolis areas (on the Eastern Hill and above the theater), defense towers, fountains, sarcophagi, burial structures, ancient roads, water channels, and residential foundations. These elements demonstrate that Tios developed not only as a harbor and trade center but also as a well-planned urban settlement.
Settlement Plan (Photo: Turkish Museums)
Archaeological Excavations and Findings
Systematic archaeological excavations at the Filyos Tios Archaeological Site began in 2006. Initial work, conducted in collaboration with the Karadeniz Ereğli Museum and the Department of Archaeology at Trakya University, involved clearing vegetation and conducting test drills. In 2007, the excavations were expanded to include the acropolis, city center, theater, and necropolis areas. Academicians, expert archaeologists, epigraphists, and students from various Turkish universities participated, and a ceramics expert from the University of Melbourne was also included in the team.
Research on the acropolis has uncovered fortress walls, tower structures, a cistern, and rubble remains dating to the Hellenistic and Roman periods. On the Eastern Hill, grave steles, column bases, and sarcophagus fragments were documented, suggesting necropolis use. In the city center, stone-paved roads, a nymphaeum, a bathhouse, and various building foundations have been revealed, with hypocaust remains under the bathhouse indicating a heating system. Near the nymphaeum, numerous pottery fragments and architectural elements have been recovered.
Aqueduct (Photo: Zonguldak İl Kültür ve Turizm Müdürlüğü)
In the ancient harbor area, submerged pedestal remains have been documented, providing insight into the city’s commercial and military roles. Near the Brick Kiln Factory, a vaulted gallery consisting of multiple compartments and rooms has been identified, though its function remains uncertain. Geophysical measurements have been carried out above the gallery area.
This comprehensive archaeological work has established Filyos Tios Archaeological Site as one of the most significant and best-preserved ancient settlements along the Black Sea coast of Türkiye.
