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Location Nicomedia

Nicomedia or Nicomedia ( ancient Greek Νικομήδεια Nicomēdeia ), today's İzmit in Turkey, was an ancient city .

Nicomedia ( 40 ° 46 ′  N , 29 ° 57 ′  E ) was founded in 264/3 BC. Chr. By King Nicomedes I of Bithynia founded as the capital of his kingdom. 74 BC After the death of Nicomedes IV , it came to the Roman Republic in will . The Roman emperor Diocletian , who had been made emperor near the city in 284, made Nicomedia his residence. From Nicomedia, Diocletian organized the most extensive persecution of Christians during the time of the Roman Empire. In his quest to save the kingdom, he saw Christians as a threat to unity. On April 30, 311, the Edict of Tolerance of Galerius was published in Nicomedia , which allowed the practice of Christianity. Emperor Constantine the Great , who resided in Nicomedia for several years, died in 337 in Achyron (a), a suburb of Nicomedia.

In 330 Constantine the Great made the former Byzantium , which he renamed Constantinople after himself , his main residence, which he expanded generously. After this change of residence, Nicomedia's importance continued to decline until the city was finally conquered by the Turkish Ottomans in 1338 and incorporated into their empire .

In modern İzmit, a systematic evaluation of the historical heritage has only begun in the last few years (as of 2008).



  • Clive Foss: Survey of medieval castles of Anatolia. Vol. 2: Nicomedia . Oxford 1996, ISBN 1-898249-07-5 .
  • Turgut H. Zeyrek: Nicomedeia: (IÖ 264/263 - IS 358). Arkeolojik Açidan Genel Bir Degerlendirme . Istanbul 2005, ISBN 975-807-097-5 .