Sofia is the capital and largest city of Bulgaria. The city has a population of 1.26 million, while over 1.5 million people live in its functional urban area. The city is located at the foot of Vitosha Mountain in the western part of the country, within less than 50 kilometres drive from the Serbian border. Its location in the centre of the Balkan peninsula means that it is the midway between the Black Sea and the Adriatic Sea, whereas the Aegean Sea is the closest to it.