inhabitants) Plovdiv (376,918) Varna (346 944) Burgas (209,985) Rousse (176,118) Stara Zagora (163,193) Pleven (121,700) Dobrich (115,861) Sliven (106,434) Shumen (103,016) Bulgaria operates a scientific base on Livingston Island in the South Shetland Islands off Antarctica . See also: List of cities in Bulgaria , Rivers of Bulgaria , and Reservoirs and