Bulgaria is a nation in Southeast Europe. Its official name is the Republic of Bulgaria. Bulgaria is bordered to the south by Greece and Turkey, to the west by Serbia and North Macedonia, and to the north by Romania. It is situated west of the Black Sea and south of the Danube River. With a land area of 110,994 square kilometers (42,855 square miles), it ranks as the sixteenth largest nation in Europe. The largest and capital city of the country is Sofia; other significant cities are Burgas, Plovdiv, and Varna.