Hellenic Republic (Ελληνική Δημοκρατία [eliniˈci ðimokraˈti.a] Ellīnikī́ Dīmokratía), is a country in Southeast Europe. According to the 2011 census, Greece's population is around 11 million. Athens is the nation's capital and largest city, its urban area also including Piraeus. Greece is strategically located at the crossroads of Europe, Asia, the Middle East, and Africa, and has land borders with Albania, the Republic of Macedonia and Bulgaria to the north, and Turkey to the northeast. The Aegean Sea lies to the east of mainland Greece, the Ionian Sea to the west, and the Mediterranean Sea to the south. Greece has the 11th longest coastline in the world at 13,676 km (8,498 mi) in length, featuring a vast number of islands (approximately 1,400, of which 227 are inhabited), including Crete, the Dodecanese, the Cyclades, and the Ionian Islands among others. Eighty percent of Greece consists of mountains, of which Mount Olympus is the highest at 2,917 m (9,570 ft).