Greece, officially the Hellenic Republic (Greek: Ελληνική Δημοκρατία), also known as Hellas (Greek: Ελλάς), is a country located in Southern and Southeast Europe, with a population of approximately 11 million as of 2016. Athens is the nation's capital and largest city, followed by Thessaloniki. Greece is located at the crossroads of Europe, Asia, and Africa. Situated on the southern tip of the Balkan Peninsula, it shares land borders with Albania to the northwest, North Macedonia and Bulgaria to the north, and Turkey to the northeast. The Aegean Sea lies to the east of the mainland, the Ionian Sea to the west, the Cretan Sea and the Mediterranean Sea to the south. Greece has the longest coastline on the Mediterranean Basin and the 11th longest coastline in the world at 13,676 km (8,498 mi) in length, featuring a large number of islands, of which 227 are inhabited. Eighty percent of Greece is mountainous, with Mount Olympus being the highest peak at 2,918 metres (9,573 ft). The country consists of nine geographic regions: Macedonia, Central Greece, the Peloponnese, Thessaly, Epirus, the Aegean Islands (including the Dodecanese and Cyclades), Thrace, Crete, and the Ionian Islands. Greece is considered the cradle of Western civilisation, being the birthplace of democracy, Western philosophy, Western literature, historiography, political science, major scientific and mathematical principles, Western drama and notably the Olympic Games. Greece's rich historical legacy is reflected by its 18 UNESCO World Heritage Sites. The sovereign state of Greece is a unitary parliamentary republic and developed country with an advanced high-income economy, a high quality of life, and a very high standard of living. A founding member of the United Nations, Greece was the tenth member to join the European Communities (precursor to the European Union) and has been part of the Eurozone since 2001. It is also a member of numerous other international institutions, including the Council of Europe, the North Atlantic Treaty Organization (NATO), the Organisation for Economic Co-operation and Development (OECD), the World Trade Organization (WTO), the Organization for Security and Co-operation in Europe (OSCE), and the Organisation internationale de la Francophonie (OIF). Greece's unique cultural heritage, large tourism industry, prominent shipping sector and geostrategic importance classify it as a middle power. It is the largest economy in the Balkans, where it is an important regional investor.