The modern lake Koumoundourou, in the southern region of the Municipality of Aspropyrgos, is identified with the site of the ancient twin ponds of Reitoi. The Reitoi were small artificial lakes created by the waters of a group of springs on the western foot of Mount Aigaleo, about 300 m north of the coast. The northern lake was devoted to Demeter, whereas the southern to Persephone. The latter has been preserved until the present day and is currently known as “lake Koumoundourou”. It marks the border between the modern towns of Haidari and Aspropyrgos. Similarly, in ancient times the Reitoi lakes constituted the boundary separating Athens and Eleusis. Old residents of the area have reported that during the 1950s both lakes existed; they had clear, perpetually changing waters with natural fish reserves. Theenlargement of the Athens-Corinth national road, which took place after World War II, reduced the surface of lake Koumoundourou significantly. The northern lake, known as “Kephalari”, was drained and filled with earth during the construction of the Aspropyrgos oil refinery in the 1950s.