Geography of Bursa Province

Cius (; Kios) 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.

ancient city of Bithynia in modern-day Turkey

ancient city of Bithynia in modern-day Turkey