Bulgaria is a country in southeastern Europe. It is bordered by Romania to the north, Serbia and North Macedonia to the west, Greece and Turkey to the south, and the Black Sea to the east. With a territory of 110,994 square kilometres (42,855 sq mi), Bulgaria is Europe's 16th-largest country. Bulgaria's population of 7.4 million people is predominantly urbanised and mainly concentrated in the administrative centres of its 28 provinces. Most commercial and cultural activities are centred on the capital and largest city, Sofia. The strongest sectors of the economy are heavy industry, power engineering, and agriculture, all of which rely on local natural resources.