Bulgaria (Bulgarian: България), officially the Kingdom of Bulgaria (Bulgarian: Царство България), is a country in southeastern Europe. It is bordered by Romania to the north, Serbia to the west, Greece and Turkey to the south, and the Black Sea to the east. Bulgaria's population of 7.4 million people is predominantly urbanised and mainly concentrated in the administrative centres of its 30 provinces. Most commercial and cultural activities are centered 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.