Claros is a prophecy center of Colophon, one of the twelve Ionic cities. Claros is built between two cities; it is 13 kilometers south of Colophon and two kilometers north of Notion. The Temple of Apollo here was a very important center of prophecy as in Delphi and Didyma. The oldest information about this sacred site goes back to the sixth and seventh centuries BC. through the Homeric Hymns. A sacred cave near the Claros Temple of Apollo, which was an important place both in the Hellenistic and Roman eras, points to the existence of a Cybelecult in earlier periods here.
The oldest piece of information about the function of the Temple of Apollo in Claros dates back to the time of Alexander the Great. According to the Greek historian Pausanias, in his dream Alexander was told that he would set up a large new city at the base of Mt. Pagos (Kadifekale). After this dream the, king consulted the Apollo oracle at Claros and asked him to interpret the dream for him. He set up the new Smyrna after the oracle gave him the go-ahead to proceed.
Many monuments were erected in the Roman period (Pompey, Lucullus, Quintus Cicero); several took place above Hellenistic foundations
The excavations conducted since 1988 at Claros, the sanctuary of Apollo that depended on Colophon, have demonstrated that there was a religious area there around a spring of fresh water from the 9th century BC. The first known construction is a round altar of the second half of the 7th century. It was covered over around the middle of the 6th century by a large rectangular altar (14,85 x 6,05 m); at the same time a marble temple was built for Apollo around the spring while Apollo’s sister, Artemis, had her own precinct and a smaller altar (3,50 x150 m): next to it were found the bases of two korai, one of which is preserved (the head is missing). There were at least four statues of kouroi dedicated to Apollo; three of them, incomplete, have been found.
Very few changes occurred in the sanctuary between the 6th and the end of the 4th century. At that time a new layout of the sacred area was conceived, with monuments on a larger scale; most probably, the plans were put into execution only after the terrible events of the beginning of the 3rd century BC. Later in the 3rd century construction began on the new altar and the new temple of Apollo ; the adyton is well preserved and allows some understanding of the importance of the spring for inspiring the oracle.
After the beginning of the Roman Province of Asia (end of the 2nd century BC), prominent citizens of Colophon helped to increase the authority of the sanctuary, the importance of the religious competitions and the fame of the oracle. To celebrate the major sacrifices before crowds consisting of Greeks and non-Greeks, four rows of iron rings attached to heavy blocks allowed a hundred victims to be killed simultaneously. Claros is the only sanctuary in the Greek world which offers a clear picture of the way priests could perform the hecatomb.