Athens (; , Athína, ; , Athēnai) is the capital and largest city of Greece. Athens dominates the Attica region and is one of the world's oldest cities, with its recorded history spanning around 3,400 years. Classical Athens, as a landlocked location was a powerful city-state that emerged in conjunction with the seagoing development of the port of Piraeus. A centre for the arts, learning and philosophy, home of Plato's Academy and Aristotle's Lyceum, it is widely referred to as the cradle of Western civilization and the birthplace of democracy, largely due to the impact of its cultural and political achievements during the 5th and 4th centuries BC in later centuries on the rest of the then known European continent. Today a cosmopolitan metropolis, modern Athens is central to economic, financial, industrial, political and cultural life in Greece. In 2012, Athens was ranked the world's 39th richest city by purchasing power and the 77th most expensive in a UBS study.
The city of Athens has a population of 664,046 (796,442 in 2004) within its administrative limits and a land area of . The urban area of Athens (Greater Athens and Greater Piraeus) extends beyond the administrative municipal city limits, with a population of 3,074,160 (in 2011), over an area of . According to Eurostat, the Athens Larger Urban Zone (LUZ) is the 7th most populous LUZ in the European Union (the 4th most populous capital city of the EU), with a population of 4,013,368 (in 2004). Athens is also the southernmost capital on the European mainland.
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 civilization. The city also retains Roman and Byzantine monuments, as well as a smaller number of Ottoman monuments.
Athens is home to two UNESCO World Heritage Sites, the Acropolis of Athens and the medieval Daphni Monastery. Landmarks of the modern era, dating back to the establishment of Athens as the capital of the independent Greek state in 1834, include the Hellenic Parliament (19th century) and the Athens Trilogy, consisting of the National Library of Greece, the Athens University and the Academy of Athens. Athens was the host city of the first modern-day Olympic Games in 1896, and 108 years later it welcomed home the 2004 Summer Olympics. Athens is home to the National Archeological Museum, featuring the world's largest collection of ancient Greek antiquities, as well as the new Acropolis Museum.
The oldest known human presence in Athens is the Cave of Schist, which has been dated to between the 11th and 7th millennium BC. Athens has been continuously inhabited for at least 7000 years. By 1400 BC the settlement had become an important centre of the Mycenaean civilization and the Acropolis was the site of a major Mycenaean fortress, whose remains can be recognised from sections of the characteristic Cyclopean walls. Unlike other Mycenaean centers, such as Mycenae and Pylos, it is not known whether Athens suffered destruction in about 1200 BC, an event often attributed to a Dorian invasion, and the Athenians always maintained that they were "pure" Ionians with no Dorian element. However, Athens, like many other Bronze Age settlements, went into economic decline for around 150 years afterwards.
Iron Age burials, in the Kerameikos and other locations, are often richly provided for and demonstrate that from 900 BC onwards Athens was one of the leading centres of trade and prosperity in the region. The leading position of Athens may well have resulted from its central location in the Greek world, its secure stronghold on the Acropolis and its access to the sea, which gave it a natural advantage over inland rivals such as Thebes and Sparta.
By the 6th century BC, widespread social unrest led to the reforms of Solon. These would pave the way for the eventual introduction of democracy by Cleisthenes in 508 BC. Athens had by this time become a significant naval power with a large fleet, and helped the rebellion of the Ionian cities against Persian rule. In the ensuing Greco-Persian Wars Athens, together with Sparta, led the coalition of Greek states that repelled the Persians, defeating them decisively at Marathon in 490 BC, and crucially at Salamis in 480 BC.
By the end of Late Antiquity, the city experienced decline followed by recovery in the second half of the Middle Byzantine Period, in the 9th to 10th centuries AD, and was relatively prosperous during the Crusades, benefiting from Italian trade. In 1458 it was conquered by the Ottoman Empire and entered a long period of decline.
Following the Greek War of Independence, Athens was chosen as the capital of the newly independent Greek state in 1834, largely due to historical and sentimental reasons. At the time it was a town of modest size built around the foot of the Acropolis. The first King of Greece, Otto of Bavaria, commissioned the architects Stamatios Kleanthis and Gustav Schaubert to design a modern city plan fit for the capital of a state.
The first modern city plan consisted of a triangle defined by the Acropolis, the ancient cemetery of Kerameikos and the new palace of the Bavarian king (now housing the Greek Parliament), so as to highlight the continuity between modern and ancient Athens. Neoclassicism, the international style of this epoch, was the architectural style through which Bavarian, French and Greek architects such as Hansen, Klenze, Boulanger or Kaftantzoglou designed the first important public buildings of the new capital. In 1896 Athens hosted the first modern Olympic Games. During the 1920s a number of Greek refugees, expelled from Asia Minor after the Greco-Turkish War (1919-1922), swelled Athens's population; nevertheless it was most particularly following World War II, and from the 1950s and 1960s, that the population of the city exploded, and Athens experienced a gradual expansion.
In the 1980s it became evident that smog from factories and an ever increasing fleet of automobiles, as well as a lack of adequate free space due to congestion, had evolved into the city's most important challenge. A series of anti-pollution measures taken by the city's authorities in the 1990s, combined with a substantial improvement of the city's infrastructure (including the Attiki Odos motorway, the expansion of the Athens Metro, and the new Athens International Airport), considerably alleviated pollution and transformed Athens into a much more functional city. In 2004 Athens hosted the 2004 Summer Olympics.