Ilissos river was considered in antiquity as the second main river of Athens, forming an horizontal landmark in its southern and eastern sides. Ancient writers mention various activities by its banks, varying from civic processes, cults -including a sanctuary dedicated to the river himself, by Ardittos hill- or social walks and philosophical endeavours in idyllic landscapes, as for Socrates and his disciples (Plato, Phaedrus 229-230, link).

While the social life around the river flourished, a number of edifices where constructed along its banks dating from antiquity to 19^th century, contributing to the accessibility between them and the efficient management of the river water (springs, bridges, water works).

Ilissos has undergone several re-arrangements on its route, commencing from antiquity and culminating in the 20^th century AD, when the river was finally channelled underground. Nowadays, it flows underneath the city of Athens, forming one of its invisible characteristics. A number of stakeholders are currently working on raising awareness on the ‘lost river’, proposing potential solutions for its sustainable re-introduction in the Athenian landscape.

This study presents the case of Ilissos river of Athens from antiquity up to our time.