An aqueduct is a structure that supplies a city and its residents with a constant supply of water. This system consists of underground water canals, water pipes, tunnels, and aqueduct bridges. The Valens Aqueduct is one of the aqueduct bridges that brings water from Thrace to Constantinople.
Between the Fourth and Third Hills of Constantinople, the Aqueduct of Valens ran over the valley east of the Church of the Holy Apostles. It stems from the late fourth century and was resurrected during the Ottoman Empire as “Bozdogan Kemeri”. The Aqueduct of Valens was more than just a series of arches; it was a vast network that has provided water to Constantinople for ages.
The Valens Aqueduct is also one of Istanbul's greatest constructions, measuring 920 meters in length and 30 meters in height. The Valens Aqueduct System took 28 years to construct, and recent study suggests that it was 336 kilometers long when completed, about three times longer than any other Roman water supply.
Valens was honored by the orator Themistius for introducing the Thracian nymphs to Byzantium. The massive Nymphaeum Maius, constructed in the Forum of Theodosius by the Prefect of Constantinople Klearchos in 372-373, most likely finished this water supply system. It was therefore finished some five years before Valens' defeat by the Goths at the Battle of Adrianople, which exposed Thrace to enemy attack.
The Valens Aqueduct was rebuilt and reconstructed several times during the Byzantine and Ottoman periods, and it served for about 1400 years, until the 18th century. Today, Atatürk Boulevard, which was constructed in the 1950s, runs beneath its arches.
Valens Aqueduct is located in the heart of Istanbul's ancient peninsula, adjacent to notable Istanbul attractions such as Pantokrator Monastery (Zeyrek Mosque), sehzade Mosque, Vefa Kilise Mosque, and Kalenderhane Mosque.