Kocaeli was founded by Phrygian King Nicomedes the 1st in 262 BC, under the name of Nicomedia. The city was the metropolis of Bithynia under the Roman Empire, and Diocletian made it the eastern capital city of the Roman Empire in 286. Nicomedia remained as the eastern (and most senior) capital of the Roman Empire until Licinius was defeated by Constantine the Great in 324. Constantine mainly resided in Nicomedia as his interim capital city for the next few years, until in 330 he declared the nearby Byzantium as Nova Roma, which eventually became known as Constantinople. Until the late XI century the city was under Byzantine rule. Than it was captured by Seljuk Turks. After capture of Constantinople in 1204 the city, together with most of the Bithynia province, became a part of the Latin Empire. It was recaptured by the Byzantines around 1235 and stayed in its borders until first half of the XIV century. The city was conquered by the Ottomans in 1338 and still is a Turkish land.