Springing from Penteli and Parnitha mountains, Kifissos is the longest river in Athens and cuts across the capital flowing southwest, up to Phaleron Bay. In Roman times the first aqueduct was constructed along its banks, and in the course of time the river served as a drainage system for rainwater. In the middle of the 20th century, its natural beauty started deteriorating due to repeated abuse from human factors: construction of sewer systems, urban sprawl, building of new highways, pollution caused by industries illegally established along its banks. Yet, in the part of the river stretching north, time seems to have stopped. Vegetation is wild, with almost no signs of urbanism. There, the river survives stubbornly, knowing well that it will have to cross the rest of the city hidden under its hard cement.