- Situated on the plain of the rivers Cladeus and Alpheus in the northwestern part of the Peloponnese
- Already occupied in the Chalcolithic age
- An Early Bronze tumulus was found underneath the Pelopion; apsidal houses
- It is not entirely clear if the site was occupied in the Mycenaean (= Late Bronze) age, but there are some finds from this period and it is certain that the hill of Kronos, which dominates the site, was already a place of worship. It may have been dedicated to Gaia (Mother Earth).
- This cult was replaced by the worship of the Olympian Zeus. He was not venerated at the hill but on the plain that was called Altis.
- According to later sources, the Olympic Games started in 776 BCE. There is evidence that the games were based on a post-Mycenaean funerary cult and were inspired by (oral traditions about) stories from the Near East, like the funeral of Enkidu in the Epic of Gilgamesh.
- The temple of Zeus and the stadium (192 meters long) must have been the oldest monuments but the oldest visible monument is the temple of Hera, Zeus' consort. This shrine was built towards the end of the seventh century BCE and measured about 50 x 19 meters. The columns, originally made of wood, were later replaced by stone pillars.
- The bouleuterion dates back to the sixth century and was expanded in the fifth century.
- The temple of Zeus was the model of the Doric building order. Built between 472 and 456 BCE by an architect named Libon of Elis, it measured 64 x 27 meters and was about 20 meters high. The eastern pediment showed the chariot race between Oenomaus and Pelops, with Zeus as judge, while the western pediment showed the fight between the Lapiths and Centaurs.
- The metopes were decorated with the Twelve Labors of Heracles.
- Inside the temple was the statue of Zeus, made by Phidias. Twelve meters high, this was one of the seven wonders of the ancient world.
- The workshop of Phidias, where he created the Zeus, has been identified.
- The Prytaneum, the meeting place of the city's prytaneis (executive magistrates), was built in the fifth century BCE.
- The temple of Hera was rebuilt in the early fourth century BCE. The metroon is about as old.
- The stadion was built in its present form in the fourth century. It could accomodate about 45,000 spectators. The Olympic Games were the most important of all panhellenic festivals.note[Cf. Pindar, Olympian Ode 1.3-7.]
- King Philip II of Macedonia, having defeated the Greeks at Chaeronea (338 BCE), added the Philipeion.
Hellenistic and Roman Age
- Third century BCE: the palaestra
- Second century BCE: the gymnasium
- Early second century CE: the nymphaeum of Herodes Atticus
- In the Roman age, the statue of Hermes, made by Praxiteles, was in the cella of the temple of Hera
- Pausanias mentions no less than sixty-nine sanctuaries and shrines
- Theodosius I (r.378-395) demanded an end to the Olympic Games, which he considered too pagan; it was his grandson Theodosius II who really put an end to the games. However, there are indications for (clandestine?) games in the sixth century.
- In the fifth century, the workshop of Phidias was converted into a Byzantine church
- The town of Olympia experienced an "Indian Summer" in the first half of the sixth century.
- The temple of Zeus was destroyed by the earthquake of 551. The site was abandoned in the seventh century.
- The sediments of the Cladeus river hid the ancient sanctuary.