The Ierothysio is a large, multifaceted architectural complex of a civil and religious nature dating from the 3rd century B.C., which remained in continuous use until late antiquity. It is characterized by an open-air peristyle courtyard surrounded by spacious halls and is located south of the Asclepieion.

It is associated with the Hierothytes, officials responsible for providing hospitality to distinguished citizens from other cities, for rituals, sacrifices, and sacred meals offered to the gods, as well as the distribution of sacrificial meat to pilgrims. It was also a kind of Pantheon, housing statues of the twelve gods, “ancient” tripods— that is, trophies from the Ithomaic Games, and a statue of the god-like hero and founder of Messene, Epaminondas, “a man renowned for his education and philosophy.”

A musical couplet engraved on a stone column with symbols of ancient music, which was discovered at Hierothysion, has been transcribed onto a European staff and set to music. The solemn, ceremonial grandeur of the melody may be related to the ritual of the sacrifice in honor of the god-like Epaminondas.