English: A 5th century B.C. sanctuary in the east of the Attic region of Greece (nearly 40km east of Athens), dedicated to the mythical King of Argos, Amphiaraos.

As the king was believed to have oracular powers, having been favoured by both Zeus and Apollo, pilgrims would visit this sanctuary for both oracular guidance and for healing. The site became very popular in the 4th century B.C., as is testified by the insensitivity of the building that occurred here at this time. Herodotus records that the responses of the Amphiareion oracle was one of only two correct answers to the test put forward by the Lydian King, Croesus. An athletic competition was also held at this site every 5 years. Because the site lies close to the edges of both Attica and Boiotia, the sacutary was frequently the subject of tussles for control between the Athenians and the Thebans. The presence of epigraphic evidence indicates that Amphiareion remained a popular cult site well into the Roman period. However, the cult ended when pagan cults were outlaws by the decrees of the Emperor Theodosius in the late 4th century. The remains of the 4th century Doric-style temple of Amphiaraos are visible, as are the remains of the altar. The altar is intriguing for being divided into sections with inscriptions to various gods and heroes, which are recorded by Pausanias. According to the geographer, the sections include one group of Hercules, Zeus, and Apollo the Healer, whilst another is for Nymphs and Pan. This presents an insight into the diversity of spirituality in antiquity. The bases of a number of dedicatory statues still survive north east of the temple. There are several notable examples from the Roman period, including one for Sulla, the dictator, and another for Marcus Agrippa, Augustus’ right-hand man.

On the site of Amphiareion, one can also see the remains of a 2nd century theatre for approximately 300 spectators, and a mid-4th century Stoa. Adjacent to the site’s sacred spring, the remains of a clepsydra are visible. This remarkably well-preserved inflow water clock is an important discovery in terms of allowing historians and archaeologists to understand ancient methods of time-keeping.