The city of Athens (Ancient Greek: Ἀθῆναι, Athênai [a.tʰɛ̂ː.nai̯]; Modern Greek: Αθήναι, Athine [a.ˈθi.ne̞] or, more commonly and in singular, Αθήνα, Athina [a.'θi.na]) during the classical period of ancient Greece (480–323 BC) was the major urban centre of the notable polis (city-state) of the same name, located in Attica, Greece, leading the Delian League in the Peloponnesian War against Sparta and the Peloponnesian League.

Classical Athens was one of the most powerful city-states in ancient Greece. It was a centre for democracy, the arts, education and philosophy, and was highly influential throughout the European continent, particularly in Ancient Rome.

There were many important city-states in Ancient Greece, but Athens was perhaps the most important and the most powerful. Athens was a great center for art, literature, philosophy, and education. It was also the first Greek city-state to adopt a fully democratic system of government.

Athens is one of the oldest named cities in the world, having been continuously inhabited for perhaps 5,000 years. Situated in southern Europe, Athens became the leading city of Ancient Greece in the first millennium BC, and its cultural achievements during the 5th century BC laid the foundations of Western civilization.