Rising majestically over the traffic on busy Atatürk Bulvarı, this limestone aqueduct is one of the city's most distinctive landmarks. Commissioned by Emperor Valens and completed in AD 378, it linked the third and fourth hills and carried water to a cistern at Beyazıt Meydanı before finally ending up at the Great Palace of Byzantium.

　　The aqueduct was part of an elaborate system sourcing water from the north of the city and linking more than 250km of water channels, some 30 bridges and more than 100 cisterns within the city walls, making it one of the greatest hydraulic engineering achievements of ancient times. After the Conquest, it supplied the Eski (Old) and Topkapı Palaces with water.