Claim: Greece was united by Alexander the Great.

Greece -LRB- Ελλάδα , -LSB- eˈlaða -RSB- -RRB- , officially the Hellenic Republic -LRB- Greek : Ελληνική Δημοκρατία , -LSB- eliniˈci ðimokraˈti.a -RSB- -RRB- , historically also known as Hellas -LRB- Ἑλλάς , -LSB- heˈlas -RSB- , modern pronunciation Ellás -RRB- , is a country in southeastern Europe , with a population of approximately 11 million as of 2015 . Athens is the nation 's capital and largest city , followed by Thessaloniki .   Greece is strategically 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 , the Republic of Macedonia and Bulgaria to the north , and Turkey to the northeast . Greece consists of nine geographic regions : Macedonia , Central Greece , the Peloponnese , Thessaly , Epirus , the Aegean Islands -LRB- including the Dodecanese and Cyclades -RRB- , Thrace , Crete , and the Ionian Islands . 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 13676 km in length , featuring a vast number of islands , of which 227 are inhabited . Eighty percent of Greece is mountainous , with Mount Olympus being the highest peak at 2918 m.   Greece is considered the cradle of Western civilization , being the birthplace of democracy , Western philosophy , the Olympic Games , Western literature , historiography , political science , major scientific and mathematical principles , and Western drama . From the eighth century BC , the Greeks were organised into various independent city-states , known as polis , which spanned the entire Mediterranean region and the Black Sea . Philip of Macedon united most of the Greek mainland in the fourth century BC , with his son Alexander the Great rapidly conquering much of the ancient world , spreading Greek culture and science from the eastern Mediterranean to the Indus River . Greece was annexed by Rome in the second century BC , becoming an integral part of the Roman Empire and its successor , the Byzantine Empire , wherein the Greek language and culture were dominant . The Greek Orthodox Church also shaped modern Greek identity and transmitted Greek traditions to the wider Orthodox World . Falling under Ottoman dominion in the mid-15th century , the modern nation state of Greece emerged in 1830 following a war of independence . Greece 's rich historical legacy is reflected by its 18 UNESCO World Heritage Sites , among the most in Europe and the world .   Greece is a democratic 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 -LRB- precursor to the European Union -RRB- 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 -LRB- NATO -RRB- , the Organisation for Economic Co-operation and Development -LRB- OECD -RRB- , the World Trade Organization -LRB- WTO -RRB- , the Organization for Security and Co-operation in Europe -LRB- OSCE -RRB- , and the Organisation internationale de la Francophonie -LRB- OIF -RRB- . 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 .