Nicomedia, the capital of the ancient Kingdom of Bithynia and later one of the most important cities of the Roman Empire, was founded in 264 BC by Nicomedes I on the site of the Astacus settlement. This strategic city, which served as the capital of the Eastern Roman Empire during the reign of Emperor Diocletian, is known for its coinage issued in the name of both Bithynian kings and Roman emperors. Today, it is located within the boundaries of modern İzmit (Kocaeli).

History

The history of Nicomedia dates back to the Astacus colony, founded by Megarians on the coast of Marmara in 712/11 BC. This early settlement, due to its strategic location in the region, attracted the attention of various powers and was occasionally destroyed. The city was refounded and greatly expanded by King Nicomedes I of Bithynia in 264 BC, taking the name Nicomedia. Quickly becoming the capital of the Kingdom of Bithynia, the city was an important cultural and commercial center during the Hellenistic Period.

After the Roman Empire gained dominance over the region, Nicomedia maintained its importance as one of the empire's leading cities. It experienced its golden age particularly when Emperor Diocletian declared the city the capital of the Eastern Roman Empire in 286 AD. Diocletian spent a significant part of his reign here and adorned the city with monumental structures. According to historical records, the Carthaginian commander Hannibal committed suicide here to avoid falling captive to the Romans, and the Roman Emperor Constantine the Great died in this city in 337 AD. The city was destroyed by a major earthquake in 358 AD but was rebuilt and continued its existence. Its being the birthplace of the writer and historian Arrian also reinforces the city's cultural significance.

Geographic Location

Nicomedia was founded in a strategic geographic location at the eastern end of the Sea of Marmara, at the head of the Gulf of İzmit. This location enabled the city to play a key role in both maritime and overland trade. Its position at the intersection of important trade routes connecting Inner Anatolia to Thrace and the Aegean increased the city's economic and military value. Being in the center of the fertile Bithynian lands also brought agricultural wealth. The gulf's natural harbor facilitated maritime trade and made the city both protected against attacks from the sea and a suitable base for naval activities. Nicomedia was also in close connection with other important ancient cities in the region, such as Nicaea (İznik) and Prusa (Bursa).

Significance in Antiquity

Nicomedia held great importance in the ancient world, politically, economically, and culturally. While it was a regional power center as the capital of the Kingdom of Bithynia, during the Roman Empire period, especially with Diocletian's choice of it as capital, it became an imperial administrative and political center. During this period, it served as the eastern center of imperial administration, a place where important decisions were made and implemented.

Economically, the city's location made it a trade hub. Thanks to its harbor opening to the Sea of Marmara, it was an important stop in maritime trade between the Black Sea and the Aegean. Its road networks ensured that goods from the interior of Anatolia reached here and were transported westward from here. The trade of regional resources such as agricultural products, timber, and minerals contributed to the city's prosperity. Culturally, it was a monumental city reflecting the architectural and artistic wealth of its era, with its grand temples, palaces, baths, and hippodrome. Its being a center where important intellectuals like Arrian were educated is an indicator of the city's cultural vibrancy. Besides the imperial cult, places of worship dedicated to local deities also demonstrated the city's religious diversity.

Coinage

Nicomedia played an important role as an active minting center in antiquity. During the Kingdom of Bithynia period, especially under Nicomedes I and his successors, they minted their own royal coinage, demonstrating both their economic independence and spreading the power and prestige of their kingdom. These coins typically featured royal portraits, local deities, and mythological figures.

During the Roman Empire period, Nicomedia continued to be one of the empire's important mints. Especially after Emperor Diocletian made the city the capital of the Eastern Roman Empire, the Nicomedia mint reached a large production capacity. Coins minted during this period featured portraits of Roman emperors, imperial symbols, and depictions dedicated to local deities (e.g., Zeus, Cybele, Demeter). The Nicomedia mint served a critical function in disseminating imperial propaganda and ensuring economic stability. The coins were widely used in regional trade and are among the important archaeological finds reflecting the city's wealth and political influence.

Nicomedia is an ancient mint represented in the NumisTR database by 802 coin varieties. The recorded coins were struck in bronze, gold, billon and silver. Authorities named on the coins include Theodosius I, Constantine I, Valens and Constantius Ii. You can browse the city's coins in the Bithynia coins list.

Archaeological Remains

Despite Nicomedia's rich ancient past, a large part of the city remains beneath modern İzmit. Natural disasters such as the great earthquake of 358 AD and the 1999 İzmit earthquake also led to the extensive destruction of ancient structures. However, some archaeological remains belonging to Nicomedia can still be found today in and around the city center.

Foundations of Roman baths, fragments of aqueducts, and remnants of city walls can be seen at various points in the modern city. Traces of the city's monumental hippodrome have also been uncovered through some excavation work. The İzmit Archaeology Museum houses important artifacts such as sculptures, mosaics, ceramics, and coins excavated from Nicomedia and its surroundings. These remains and the artifacts in the museums help us understand the ancient city's splendor and daily life. The fact that a large part of the city still lies beneath modern development holds significant potential for future archaeological discoveries.

Today

The ancient city of Nicomedia is located today within the boundaries of the İzmit district, part of Turkey's Kocaeli province. Modern İzmit is a bustling industrial and commercial city, conveniently located approximately 100 kilometers from Istanbul. Access to the city by road and rail is quite easy. The remains of the ancient city are integrated into the modern urban fabric; it is possible to encounter architectural elements or foundation remnants from antiquity in some parks, squares, or construction sites. The İzmit Archaeology Museum showcases the cultural heritage of ancient Nicomedia, offering visitors a valuable window into the city's past.