Eleusis is a town and municipality in West Attica. It is situated about 18 km northwest from the center of Athens. It is located in the Thriasian Plain, at the northernmost end of the Saronic Gulf. It is best known for having been the site of the Eleusinian Mysteries, one of the most famous religious ceremonies of the ancient Greek religion, and the birthplace of Aeschylus, one of the three great tragedians of antiquity. Today Eleusis is a major industrial center with the largest oil refinery in Greece.
Although aggravated by movement of the ship bay of Eleusis, in recent years have seen a slow, yet noticeable improvement in water quality. According to recent measurements, progressively reduced concentrations of nitrates, nitrites and ammonia, while increasing transparency and dissolved oxygen.