Nicomedia

Nicomedia was an ancient city located in what is now İzmit, Turkey. Founded in 264 BC by Nicomedes I of Bithynia, it served as the capital of the Kingdom of Bithynia. Due to its strategic location on the major trade routes between Asia and Europe, and its proximity to the Sea of Marmara, Nicomedia rapidly grew into a significant economic and political center.

Under the Roman Empire, Nicomedia became one of the empire's most important cities. Diocletian, in 286 AD, designated it as the eastern capital of the Roman Empire during the Tetrarchy. This period saw extensive building programs including imperial palaces, public baths, amphitheaters, and mints, significantly expanding and embellishing the city. For a time, Nicomedia was arguably the most prominent city in the Eastern Roman Empire, surpassing even Byzantium (later Constantinople) in importance.

Nicomedia suffered from a major earthquake in 358 AD, causing significant damage and loss of life. It was rebuilt, but never fully regained its previous status. Constantinople's growing prominence and eventual establishment as the sole capital diminished Nicomedia's importance.

Throughout its history, Nicomedia played a significant role in the early development of Christianity. It was the site of numerous conflicts between Christians and pagans, including the Diocletianic Persecution, one of the most severe persecutions of Christians in Roman history. The historian Eusebius of Caesarea documented many of these events. Several important early Christian figures were associated with Nicomedia, including Saint Pantaleon and Saint George.

In the later Roman and Byzantine periods, Nicomedia continued as an important regional center, although it was often subject to invasions and political instability. The city fell to the Ottoman Turks in the 14th century and was renamed İznikmid. It remains a significant city in modern Turkey, known as İzmit. While much of ancient Nicomedia is buried beneath the modern city, archaeological excavations have revealed traces of its rich past.