Nicomedia

Nicomedia was a major ancient Greek city located in northwestern Asia Minor. It is situated in the modern-day country of Turkey.

The city served as a vital center for trade, politics, and military power for many centuries. It functioned as the metropolis and capital of the Roman province of Bithynia. Because of its location, it remained important even after other cities rose to power. Its history spans from early Greek colonies to the rise of the Ottoman Empire.

The city's origins date back to 712–711 BC. It was founded as a Megarian colony and was originally named Astacus, which means "lobster." After the city was destroyed by Lysimachus, Nicomedes I of Bithynia rebuilt it in 264 BC. He renamed the city Nicomedia. This reconstruction established the city as a key urban center in the region. Over time, it grew into a cosmopolitan hub with diverse populations and complex infrastructure.

Nicomedia was famous for its sophisticated public works and amenities. The city relied on a bountiful water supply provided by two or three aqueducts. One of these structures was built during the Hellenistic period.

The Roman governor Pliny the Younger noted that the citizens spent 3,318,000 sesterces on an unfinished aqueduct. This massive expenditure caused engineering troubles and led to investigations into corruption. Other urban features included a forum, a theater, and a temple of Demeter on a hill.

The city reached a peak of political importance during the Roman Empire. In 286 AD, Emperor Diocletian chose Nicomedia as the eastern and most senior capital. This was part of the Tetrarchy, a system where power was shared among four rulers.

Diocletian transformed the city by building an enormous palace, an armory, a mint, and new shipyards. However, this era also saw the Diocletianic Persecution of Christians. In 303 AD, Diocletian ordered the destruction of a newly built church in Nicomedia. This event caused panic and was followed by two major fires that damaged the imperial palace.

Political shifts continued as the Roman Empire changed. The Tetrarchy ended in 324 AD after the Battle of Chrysopolis. Constantine the Great defeated his co-emperor Licinius to become the sole ruler. Constantine used Nicomedia as his interim capital for six years. In 330 AD, he moved the capital to nearby Byzantium, which he renamed Constantinople. Despite this move, Nicomedia remained important because it sat at the convergence of roads leading to the new capital. The city later faced a massive earthquake in 358 AD, which forced a smaller-scale rebuilding.

Nicomedia was also a place of religious and cultural diversity. Evidence shows a Jewish presence, including migrants from Macedonia. Inscriptions from a third-century tomb feature symbols like the menorah, shofar, and lulav.

The city also hosted famous figures, such as the historian Arrian. In the later Byzantine period, the city was a major military base. It played a role in campaigns against the Caliphate and hosted Crusaders in the 1080s. During the Fourth Crusade, the city was briefly held by the Latin Empire.

The city eventually fell to the Ottoman Empire through a series of conflicts. After the Byzantine defeat at the Battle of Bapheus in 1302, the rising Ottoman beylik began to threaten the area. Nicomedia faced sieges and blockades in 1304 and 1330. It finally fell definitively to the Ottomans in 1419 AD. Today, the ancient ruins are mostly buried beneath the modern city of İzmit. Recent excavations near the site of Diocletian's Palace cover approximately 60,000 square meters.