The eschara is a sizable altar and, according to ancient inscriptions concerning the sacrifices to Demetra and her daughter Persephone, an ‘underground’ one. Situated northeast of the temple of Artemis Propylaea and Poseidon Patroos, it stands distinctly apart from the courtyard’s paved surface by a layer of stones that shape an uneven rectangle. The dimensions of this rectangle vary, extending from six metres on its southern edge to eight and a half metres on the northern side. Within this rectangular boundary, the ground is unpaved, centering on a brick-built rectangular altar below the surface level. A notable architectural detail is a small, fifteen-centimetre wide ledge midway up the altar walls, designed to hold a metal eschara for the placement of sacrificial carcasses, essential in the veneration of the goddesses, particularly for the complete burning of piglets. Archaeological evidence suggests the eschara’s establishment during the Roman period is likely contemporary with the courtyard’s paving. However, this spot was previously home to older structures, possibly earlier sanctuaries or altars.
