Bulgaria, Republic of, republic in south-eastern Europe, known from 1946 to 1990 as the People's Republic of Bulgaria and now known as the Republic of Bulgaria. Situated in the Balkan Peninsula, Bulgaria is bordered on the north by Romania, on the east by the black Sea, on the south by Turkey and Greece, and on the west by Serbia and the Former Yugoslav Republic of Macedonia. Once an independent kingdom, Bulgaria was controlled by the Communist Party from 1946 until 1990, when a multi-party system was adopted. The area of Bulgaria is 110,912 sq km. The capital and largest city is Sofiya.