Amphiaraeion is situated in Horopos, 48 km from Athens.

The Amphiaraeion was a sacred place and an oracle, dedicated to the ancient hero Amphiaraos who, according to legends, had great prophetic and healing power. Founded in the 5ththe century BC, it operated as both an oracle and an infirmary. Here used to be organized the Big Amfiaraeia in honor of the namesake deified hero.

Today in the archaeological site you can see the ruins of the Doric temple and the ancient stone theater of the 2nd century B.C.that has a very well preserved stage. What's more, you have the chance to see the remains of the grand lodge of the Temple and the altar.