The route of the river and associated architecture
Emanating from the north-western slopes of Hymettus mountain and discharging in Faliro gulf after concurring to Kifissos, Ilissos river run outside the eastern and southern walls of the ancient city of Athens moving west, draining rainwater in its route by converging seasonal streams. One of its branches run through the contemporary Kaisariane monastery area (and gorge), while the northern one through the byzantine monastery of St. John the Theologian, at the south of Cholargos area. In that area several aqueducts were built parallel to the route of the river, most prominent of which was the Peisistrateian (540-530 BC, link) that carried water from Hymettus to the city centre.
Heading south, Ilissos’ bed proper flows under the contemporary avenues and the modern-day ‘Ilissia’ area. It passes by the Panathenaic Stadium (Vasilissis Sofias Avenue), at a place where a three-arched roman bridge used to stand. That was an offer by Herodes Atticus (2nd c. AD). Although in 1738 the travellers report that architectural members from the bridge were used to build the houses nearby, the bridge survived until 1778 and was rebuilt in 1870’s along with the Panathenaic stadium, that would host the first modern Olympic Games in 1896. The bridge was demolished in the mid 20th century during the river encasement and the construction of the square in front of the stadium.
The river then flows by the byzantine chapel of St. Foteini “of Ilissos”, built on top of the ancient sanctuary of Hekate and by the sanctuary of Pan. At this site a shallow marshland called Vatrachonisi (= Frog Island) was located until the 19th century, opposite Ardittos hill, between two branches of the river (another patch of land between the split course of the river is spotted north-west of the Panathenaic stadium). In 1897 a great flood caused the submersion Vatrachonisi and diversion of the river to the south, into its medieval bank, in order to forestall future threats.
The area by St. Foteini, is one of the few sites where the river is still traceable today, forming an interesting but unattended park. In the 19th c. a bridge was built at this point, joining the two banks of the river, and it is still visible today, bearing the crest of King Otto, the first king of Greece and the name of the Mayor of Athens Ι. Koniaris (1801-1872). In this area, a rock cluster formed a deep chasm of 4-5 meters, shaping small waterfalls. Kallirhoe spring, one of the most renowned waterworks in ancient Athens, was located in this area as well. In the last quarter of the 6th century B.C. its waters were channelled to the so-called Enneakrounos fountain (fountain with nine water-spouts), often mentioned and depicted in ancient times.
Ilissos waters are still used today to water the National Garden of Athens, at the north-east side of this area. The river then moves to the south-eastern flank of the roman temple of Olympian Zeus (a visitable and monumental archaeological site), leaving behind the ‘parilissian sancturies’ towards Faliron.
After converging with Eridanos, Ilissos could be afterwards traced under Thisseos Avenue (Kallithea area), where occasionally overflows after torrential rain, causing various problems. Its original course in antiquity turned north-west to join Kifissos, heading south towards the sea. In the beginnings of the 20th c. its route was diverted, routed again to the Faliro gulf, however a few kilometres eastern of Kifissos estuary.
Covering of the river
Ilissos’ gradual covering began in the late 19th c., starting from its southern branch in Mets area (‘Vatrachonisi’), after the devastating storm flood of 1897. This should not have been a completely random event. The banks of the river were systematically exploited by the Municipality of Athens from the 19th c. until 1920’s, as a source for sand and gravel, used to build the roads of the capital. This practice caused severe degradation in certain areas making them vulnerable to flooding and prone to retain stagnant waters; a situation exacerbated from the fact that Ilissos catered for sewage for a part of Athens, since early 20th century.
Thus, following the growth of the population in the capital and the urgent need for more space in the urban environment, the part of the river up to the Panathenaic stadium was buried between 1939-1948; a decision made by Metaxas, with the legendary expression: “Today we bury Ilissos“.
Ilissos was further degraded and polluted by sewage and garbage, turning into a resource in desperate need of sanitization. This was made possible through the underground channeling of the river, completed in the 1960’s, coinciding with the massive introduction of cars in Athens. The “Anti-Flooding and Drainage Programme of Athens” project was funded by the Marshall Plan given to Greece after WWII. Unregulated expansion of builings near the river sources at Hymmetus completed the scenery and Ilissos gave its place to a cluttered built environment and avenues full of cars…
By the late 1960’s the river had been largely covered and its banks turned subterranean. A well known Chatzidakis’ song of 1955 asking ‘What’s the name of the river’ probably demonstrates that Athenians had already started forgetting Ilissos by that time (link)
Nowadays, only parts of its original route remain uncovered, namely at Goudi park; at Kallirhoe spring (Mets area) and at P. Tsaldari Avenue (Kallithea area).