Several rivers meet the Vardar within the city boundaries. The largest is the Treska, which is long. It crosses the Matka Canyon before reaching the Vardar on the western extremity of the City of Skopje. The Lepenec, coming from Kosovo, flows into the Vardar on the northwestern end of the urban area. The Serava, also coming from the North, had flowed through the Old Bazaar until the 1960s, when it was diverted towards the West because its waters were very polluted. Originally, it met the Vardar close to the seat of the Macedonian Academy of Sciences and Arts. Nowadays, it flows into the Vardar near the ruins of Scupi. Finally, the Markova Reka, the source of which is on Mount Vodno, meets the Vardar at the eastern extremity of the city. These three rivers are less than long.