[[Image:Tetrarchy map3.jpg|right|thumb|400px|Nicomedia, Chalcedon, Byzantium, and Nicea in First tetrarchy, ca. 293 AD]]'''Nicomedia''' was a city in Anatolia, near Constantinople and [[Nicea]], that was the interim capital for [[Constantine the Great]] while the city of [[Byzantium ]] was re-built and became Constantinople. During the early days after Roman recognition of Christianity Nicomedia was a [[see]] serving the imperial household. In modern days the city continues to exist as Izmit in the Turkish Republic.