Athens has been the center of Greek civilization for some 4,000 years. The capital of modern Greece, it’s still dominated by 5th-century-B.C.E. landmarks, including the Acropolis, a hilltop citadel topped with ancient buildings such as the colonnaded Parthenon temple. But it’s also a contemporary city, and it’s not uncommon for the nightlife hubs of Kolonaki, Psiri and Gazi to stay busy until dawn. 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. The dominant feature of Athens's climate is alternation between prolonged hot and dry summers and mild winters with moderate rainfall. The municipality (City) of Athens has a population of 664,046 people. The city is a world centre of archaeological research, and has many institutes and museums dedicated to that research. Athens has been a destination for travellers since antiquity. Over the past decade, the city's infrastructure and social amenities have improved, in part because of its successful bid to stage the 2004 Olympic Games.