In western Peloponnese, in the beautiful valley of the Alpheios river, lies the most celebrated sanctuary of ancient Greece. Dedicated to Zeus, the father of the gods, it sprawls over the southwest foot of Mount Kronios, at the confluence of the Alpheios and the Kladeos rivers, in a lush, green landscape. Although secluded near the west coast of the Peloponnese, Olympia became the most important religious and athletic centre in Greece. Its fame rests upon the Olympic Games, the greatest national festival and a highly prestigious one world-wide, which was held every four years to honour Zeus. The origin of the cult and of the festival went back many centuries. Local myths concerning the famous Pelops, the first ruler of the region, and the river Alpheios, betray the close ties between the sanctuary and both the East and West.
The earliest finds in Olympia are located on the southern foot of Mount Kronios, where the first sanctuaries and prehistoric cults were established. A large number of pottery sherds of the Final Neolithic period (fourth millennium BC) were found on the north bank of the stadium. Traces of occupation of the three periods of the Bronze Age were identified in the greater area of the Altis and new museum. A great tumulus of the Early Helladic II period (2800-2300 BC) was discovered in the lower strata of the Pelopion, while several apsidal structures belong to the Early Helladic III period (2150-2000 BC).
It is traditionally believed that in approximately 1200 BC the region of Olympia was settled by Aetolians under the leadership of Oxylos, who founded the state of Elis. The first planned sanctuary dedicated to local and Pan-Hellenic deities was probably established towards the end of the Mycenaean period. The Altis, the sacred enclosure with its shady oaks, planes, pines, poplars and olive-trees, was first formed during the tenth and ninth centuries BC, when the cult of Zeus was probably established. Olympia was subsequently devoted exclusively to worship and for many centuries had no other structures except for the Altis, a walled precinct containing sacrificial altars and the tumulus of the Pelopion. The numerous votive offerings, mostly figurines, bronze cauldrons and tripods were placed outdoors, on trees and altars. The first figurines representing Zeus, the master of the sanctuary, date to the Geometric period.
In 776 BC, Iphitos, king of Elis, Kleosthenes of Pisa and Lykourgos of Sparta reorganized the Olympic Games in honour of Zeus and instituted the sacred ekecheiria, or truce. Soon the quadrennial festival acquired a national character. The great development of the sanctuary began in the Archaic period as shown by the thousands of votive offerings - weapons, figurines, cauldrons etc - dating from this period. This is when the first monumental buildings were constructed - the temple of Hera, the Prytaneion, the Bouleuterion, the treasuries and the first stadium.
The sanctuary continued to flourish into the Classical period, when the enormous temple of Zeus (470-456 BC) and several other buildings (baths, stoas, treasuries, ancillary buildings) were erected, and the stadium moved to the east of its Archaic predecessors, outside the Altis. The countless statues and precious offerings of this period were unfortunately lost, as the sanctuary was pillaged several times in antiquity and especially under Roman rule. In the Hellenistic period the construction of lay buildings, such as the gymnasium and palaestra, continued, while in Roman times several existing buildings were refurbished and new ones built, including hot baths, luxurious mansions and an aqueduct. Many of the sanctuary's treasures were removed and used for the decoration of Roman villas.