Eleusis occupied a fertile coastal plain west of Athens, with settlement documented from the second millennium BCE and earlier activity in the area. Its enduring fame came from the sanctuary of Demeter and Kore, or Persephone, divinities associated with grain, fertility, seasonal renewal, and the boundary between life and death. A local cult developed into the Eleusinian Mysteries, among the most prestigious religious initiations in the Greek world. The rites promised initiates a transformed understanding of mortality, but their guarded secrecy prevents modern historians from reconstructing the ceremony in full.

Athens brought Eleusis into its territory and integrated the sanctuary into civic and interstate life. Initiates gathered in Athens and traveled along the Sacred Way to Eleusis through a sequence of purifications, processions, sacrifices, fasting, and ritual actions. Participants could include women, foreigners, and enslaved people if they met religious requirements and understood Greek, giving the cult an unusually broad reach while still operating within unequal ancient society. The Telesterion, repeatedly enlarged, accommodated crowds who witnessed sacred objects and performances known only through indirect literary and archaeological evidence.

Persian forces destroyed the sanctuary in 480 BCE, and Greek rebuilding culminated in major Classical works associated with Periclean Athens. Hellenistic and Roman patrons added walls, gates, fountains, arches, and new approaches; Roman emperors and elites were among the initiates. The sanctuary declined as imperial religious policy favored Christianity, and Gothic attack in the late fourth century contributed to its end. Later settlement, stone reuse, burial, farming, and modern industrial development transformed Elefsina, leaving the ancient precinct embedded in a city known for refineries, factories, labor, and environmental pressure.

Excavation exposed the Telesterion foundations and rock-cut seating, Greater and Lesser Propylaea, Ploutonion, Kallichoron Well, fortification walls, Roman courts, and sections of the Sacred Way. Most structures survive as foundations or partial masonry rather than complete buildings. Some columns and blocks have been re-erected, walls consolidated, and fragments arranged to clarify plans; modern paths, platforms, shelters, labels, and the archaeological museum support interpretation. These interventions are distinguishable from ancient fabric. The site's fragmentary form cannot reveal the secret ritual spectacle without cautious inference.

The Ephorate of Antiquities of West Attica, part of Greece's Ministry of Culture, manages the archaeological site and museum. Access, museum galleries, and conservation areas can change with projects and operating schedules. Interpretation should resist inventing a detailed script for the Mysteries or presenting every ruin as Classical, because Mycenaean, Archaic, Classical, Hellenistic, Roman, late antique, and modern layers overlap. Eleusis gains meaning from the relationship among landscape, procession, architecture, secrecy, agriculture, and living industrial Elefsina, with excavated, restored, and reconstructed elements identified separately.