Athens ( ATH-inz) is the capital and largest city of Greece. A major coastal urban area in the Mediterranean, Athens is also the capital of the Attica region and is the southernmost capital on the European mainland. With its urban area's population numbering over three and a quarter million, it is the eighth largest urban area in the European Union. The Municipality of Athens (also City of Athens), which constitutes a small administrative unit of the entire urban area, had a population of 643,452 (2021) within its official limits, and a land area of 38.96 km2 (15.04 sq mi).

Athens is one of the world's oldest cities, with its recorded history spanning over 3,400 years, and its earliest human presence beginning somewhere between the 11th and 7th millennia BC. According to Greek mythology the city was named after Athena, the ancient Greek goddess of wisdom, but modern scholars generally agree that the goddess took her name after the city. 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. For this reason, it is often regarded as the cradle of Western civilization and the birthplace of democracy in its own right independently from the rest of Greece.

In modern times, Athens is a large cosmopolitan metropolis and central to economic, financial, industrial, maritime, political and cultural life in Greece. It is a Beta-status global city according to the Globalization and World Cities Research Network, and is one of the biggest economic centers in Southeastern Europe. It also has a large financial sector, and its port Piraeus is both the 2nd busiest passenger port in Europe, and the 13th largest container port in the world. The Athens metropolitan area or Greater Athens extends beyond its administrative municipal city limits as well as its urban agglomeration, with a population of 3,638,281 (2021) over an area of 2,928.717 km2 (1,131 sq mi).

The heritage of the Classical Era is still evident in the city, represented by ancient monuments, and works of art, the most famous of all being the Parthenon, considered a key landmark of early Western culture. The city also retains Roman, Byzantine and a smaller number of Ottoman monuments, while its historical urban core features elements of continuity through its millennia of history. Athens is home to two UNESCO World Heritage Sites, the Acropolis of Athens and the medieval Daphni Monastery. Athens is also home to several museums and cultural institutions, such as the National Archeological Museum, featuring the world's largest collection of ancient Greek antiquities, the Acropolis Museum, the Museum of Cycladic Art, the Benaki Museum, and the Byzantine and Christian Museum. Athens was the host city of the first modern-day Olympic Games in 1896, and 108 years later it hosted the 2004 Summer Olympics, making it one of five cities to have hosted the Summer Olympics on multiple occasions.