Sliven, town in eastern Bulgaria, capital of Sliven Province, at the southern foot of the Balkan Mountains. It is a manufacturing centre with products that include textiles, glass, carpets, electrical equipment, wood and metal products, wines, and foodstuffs. Because of its strategic position at the entrance of mountain passes, the site has been settled since Roman times. The town was under Turkish occupation from the 15th to 19th century and then passed to the Russian empire. Population 100,695 (2001).