Νικομήδεια was an ancient city located in what is now modern-day Turkey. Founded by the Roman Emperor Diocletian in the late 3rd century AD, it served as an important administrative center in the region. The city was named after Nicomedes IV, the last king of Bithynia, and became a significant hub for trade and culture. The city was known for its impressive architecture, including public buildings, temples, and a large amphitheater. It played a vital role in the early Christian church and was the site of several important events in Christian history. Today, the ruins of Nikómideia can be explored, offering insights into its rich past.