Greece, officially the Hellenic Republic, historically also known as Hellas, is a country in southeastern Europe. Athens is the nation's capital; Greece is strategically located at the crossroads of Europe, Asia, and Africa. Eighty percent of Greece is mountainous, with Mount Olympus being the highest peak. Ancient 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 organized into various independent city states, which spanned the entire Mediterranean region and the Black Sea. 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. Falling under Ottoman dominion in the mid-15th century, the modern nation state of Greece emerged in 1830 following a war of independence.