Olympia developed where the Alpheios and Kladeos rivers meet in the western Peloponnese. Prehistoric occupation preceded a sanctuary that became centered on Zeus by the early Iron Age. Tradition dates the first recorded Olympic contest to 776 BCE, though ritual and competition evolved over time. The Altis, a sacred grove enclosed from surrounding facilities, gathered altars, temples, treasuries, statues, and administrative buildings. Olympia was not a permanent city on the scale of Athens; it was a Panhellenic sanctuary periodically filled by athletes, officials, delegations, merchants, spectators, and pilgrims from Greek communities.

The games formed part of a religious festival to Zeus. Competitors trained and swore oaths, sacrifices structured the celebration, and victors received olive crowns rather than prize money from Olympia itself. Events expanded from a foot race to wrestling, boxing, pentathlon, chariot racing, and other contests. Political rivalries did not disappear, but the sacred truce facilitated travel. Monumental offerings advertised victories and civic power. The stadium, hippodrome, gymnasium, palaestra, guest houses, council building, and workshops supported an institution whose calendar helped Greeks measure time by numbered Olympiads.

The great Temple of Zeus, built in the fifth century BCE, housed Pheidias's colossal gold-and-ivory seated statue, later counted among the Seven Wonders. Pedimental sculptures and metopes presented heroic and moral themes. The older Temple of Hera, treasuries, Philippeion, and numerous dedications recorded centuries of patronage. Roman rulers added baths, residences, and monuments while maintaining the festival. Imperial Christian policy ended pagan cult and the ancient games by the late fourth century. Earthquakes, floods, river deposits, reuse, and abandonment brought buildings down and buried much of the sanctuary.

German-led excavation began systematically in 1875 and revealed the plan, sculpture, bronzes, inscriptions, and athletic facilities. Museums now protect the most vulnerable originals, including the Temple of Zeus sculpture and Nike of Paionios. Limited anastylosis has re-erected selected columns and architectural elements, but most monuments remain conserved ruins. Since 1936 the flame for the modern Olympic Games has been lit near the Temple of Hera in a deliberately modern ceremony inspired by antiquity. Wildfire and flooding are serious threats; fires in 2007 damaged the surrounding landscape but spared the principal monuments.

UNESCO inscribed Olympia in 1989, and the Greek Ministry of Culture manages the archaeological site and museums through the regional ephorate. Ticketed access follows paths through the Altis, stadium, training buildings, temples, and later remains. Much stone lies where structures collapsed or has been arranged after excavation, so the site is authentic without appearing intact. Reconstruction is selective and identifiable. Olympia's historical force comes from the union of sanctuary, athletics, art, interstate competition, and later global revival, while its physical record also demonstrates how excavation and modern ceremony shape the meaning of an ancient institution.