Cieszyn is a border town in southern Poland on the east bank of the Olza River, and the administrative seat of Cieszyn County, Silesian Voivod…Cieszyn is a border town in southern Poland on the east bank of the Olza River, and the administrative seat of Cieszyn County, Silesian Voivodeship. The town has 33,500 inhabitants, and lies opposite Český Těšín in the Czech Republic. Both towns belong to the historical region of Cieszyn Silesia, and formerly constituted the capital of the Duchy of Cieszyn as a single town.