Cius

This article is about the ancient Greek city. For Roman fort in Moesia, see Cius (castrum). For tablet device from Cisco, see Cisco Cius.

Cius
Currently Gemlik, Turkey
Location within Turkey
40.432468°N 29.156389°E / 40.432468; 29.156389
Location	Anatolia, in present-day Turkey
Region	Bithynia

Cius (/ˈsaɪəs/; Ancient Greek: Kίος or Κῖος Kios; Currently Gemlik, Turkey) was an Ancient Greek city bordering the Propontis (now known as the Sea of Marmara), in Bithynia and in Mysia (in modern northwestern Turkey). The city was later renamed to Prusias after King Prusias I of Bithynia, who once restored the city.