Bulgaria, officially the Republic of Bulgaria, is a country in southeastern Europe. It is bordered by Romania to the north, Serbia and Macedonia to the west, Greece and Turkey to the south, and the Black Sea to the east. With a territory of 110,994 square kilometers (42,855 sq mi), Bulgaria is Europe's 14th-largest country. Bulgaria's population of 7.4 million people is predominantly urbanised and mainly concentrated in the administrative centres of its 28 provinces. The country's current political structure dates to the adoption of a democratic constitution in 1991. Bulgaria has been traditionally a Christian state since the adoption of Christianity as state religion in 865, and therefore the dominant confession is Eastern Orthodoxy of the Bulgarian Orthodox Church, but the government guarantees the free exercise of religion.