Eleusis, ancient Greek city famous as the site of the Eleusinian Mysteries. Situated in the fertile plain of Thria about 14 miles (23 km) west of Athens, opposite the island of Salamis, Eleusis was independent until the 7th century bc, when Athens annexed the city and made the Eleusinian Mysteries a major Athenian religious festival. After the Peloponnesian War, when the Thirty Tyrants were expelled from Athens and briefly occupied Eleusis, the city was again independent (403), but Athenian hegemony was restored within two years. The Gothic leader Alaric destroyed Eleusis in ad 395, and the site remained deserted until the 18th century, when it was revived as the modern town of Eleusis (Greek Lepsina), now an industrial suburb of Athens.
The Greek Archaeological Society, excavating the site after 1882, laid bare the whole of the sacred precinct, which included the Great Propylaea, a 2nd-century-ad copy of the central building of the Propylaea on the Acropolis of Athens. It also traced its extensions at various periods and revealed successive stages in the structure of the Telesterion, or Hall of Initiation, first built in late Mycenaean times, before 1000 bc.