"The 921-meter long Valens Aqueducts - a prominent landmark in Istanbul's Fatih district - played a vital role in supplying water to the people of the Byzantine and Ottoman empires. The Roman Emperor, Valens ordered the construction of the aqueduct in late 4th century AD to feed water from the hills beyond Istanbul to hundreds of underground cisterns inside the city, including the famous Basilica Cistern located opposite the Hagia Sophia. The best place to view the towering stone aqueduct today is where it crosses the busy Ataturk Boulevard near the Mosque of Şehzade. The boulevard is the main thoroughfare between Taksim Square and the Aksaray neighborhood."