Amphiaraeo is an archaeological site of Attica. It is situated on a hill 6 kilometers southeast of Oropos, a bit northwest of Kalamos. There was a sacred place and an oracle dedicated to the mythical hero Amphiarao. It was founded in the 5th century BC when the wider area of ​​Oropos belonged to the Athenians. An oracle and a sanatorium were operating in the area. In the area were the great Amphiaraea, a major celebration held every five years in honor of Amphiaraos, and included athletic competitions.

The temple of Amphiaraos was a temple at the front, Doric temple. Its dimensions were 28 by 14 meters. Inside the temple was the statue of Amphiaraus. There were five groups of statues depicted in the temple in the temple:

Hercules, Zeus and Apollo

Heroes and their wives

Estia, Hermes and Amphiarao

Aphrodite, Pan, Iaso, and Athena

The nymphs and the river deities of Acheloos and Kifissos

An important building of the archaeological site is the ancient theater. It was built in the 2nd century BC. It was made of stone with wooden seats. It had a capacity of more than 300 seats but only the scene survives today.
In front of the stage of the theater is the large gallery, 11 meters wide and 110 meters long, with 39 Doric columns in total. There were separate bathrooms at the two ends of the gallery for men and women. Close to the temple was a marble hourglass (hydraulic clock), a rare archaeological sample.

Source: CHRIS.P-LifeAfterGravity