The Mycenaean complex (14th century BC) was excavated and well restored in the 1960s and 1970s under the direction of Prof. Dakaris. S.Dakaris considers this complex to be the oracle of the dead described by Homer and Herodotus. Priestesses and priests made contact with the underworld in rituals in which various intoxicating substances were used. The living should be able to get in touch with the dead. From the complex you can see the valley of the Acheron, the river of the dead of antiquity. See also de.wikipedia.org/wiki/Nekromanteion
It is certainly an impressive and historically valuable site, but the entrance fee of €10 per person is a bit steep. After our confused looks at the ticket counter, our 25-year-old son still thought he was a child.