Ploutonion
To the west of the Lesser Propylaea, at the northeast foot of the acropolis hill, two successive shallow caves are formed in the rock, which probably constituted the core of the primordial cult.
On the north wall of the smallest cave an aperture can be seen and on its outer side a stair of six steps is preserved cut in the rock. The stair leads outside the Ploutonion enclosure, in a lower lying area, where there is a deep well-like pit.
In front of the largest cave lie the poros foundations of a relatively small temple, measuring about 5,12x6.80m, which was decicated to Pluto. It consists of a rectangular cella (main temple) with projecting pilasters (temple «in antis») and is dated to the 4th cent. BC. This temple replaced an earlier one of the 6th cent. BC, that measured 3,40x4,70m, incorporating its remains.
In a later phase, in the 4th cent. BC, the area of the Ploutonion was demarcated by the construction of a triangular retaining enclosure built in the isodomic system of poros blocks, with a small porch at its southeast end. The enclosure separated the precinct of Pluto from the rest of the Sanctuary.
On the inside of the enclosure there is a deep circular pit which most probably was associated with cult rituals. Two votive reliefs that were found in this area and bear representations related to Pluto and Persephone, attest that the temple was the Ploutonion.
Although it is not clear how the caves were used and what ritual was potentially associated with them, it seems that their occurrence in this particular location was decisive in choosing it for the erection of Pluto’s precinct. Their morphology might have served as a suitable setting for the representation of the sacred drama of Persephone’s annual return from Hades.
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