The Ilissos is a river in ancient Greece, flowing through the region of Attica. It originates from the hills near Mount Hymettus and eventually empties into the Saronic Gulf. The river was significant in ancient times, serving as a natural boundary and a source of water for the surrounding areas. In classical literature, the Ilissos is often mentioned in the works of famous writers like Plato and Pindar. The river was also associated with various myths and was a popular spot for philosophical discussions and gatherings, reflecting its importance in the cultural life of ancient Athens.