Valens Aqueduct (Bozdoğan Kemeri) — Istanbul
Valens Su Kemeri · Aqueduct of Valens · Bozdoğan Aqueduct · Constantinople Aqueduct
Late Roman to Ottoman (4th–19th c. CE)·East Roman (Byzantine) Constantinople·🇹🇷 Marmara, Istanbul, Fatih, Turkey
About
About Valens Aqueduct (Bozdoğan Kemeri) — Istanbul
971-m Byzantine double-tier aqueduct bridging the valley between the Third and Fourth Hills of Constantinople, completed 373 CE under Emperor Valens and restored by Justinian, Basil II and Süleyman. The 61-m high? 6 m/s flow to 158 cisterns including the Basilica Cistern (Yerebatan). Underground Thracian channels 120 km with inverted siphon at Kurşunlugerme 175-m long bridge 37-m high exemplify late Roman surveying over two mountain ranges. Atatürk Boulevard now passes under central arch.
Why it mattersHeadwork of longest Roman hydraulic network (426 km) surpassing Zaghouan; only surviving multi-tier late Roman aqueduct in a megacity, bridging classical to Byzantine engineering.
Open questions
Mysteries & theories
Mysteries
- 01How 0.15% grade held over 240 km with two mountain crossings
- 02Whether 175-m Kurşunlugerme siphon needed lead or stone pipe
Theories
- 01Thracian water as imperial legitimacy display rivaling old Rome
- 02System intended to sever Thracian spring independence and bind hinterland
Theories are interpretations, not findings. The seal above tells you how much scholarly weight the place carries.
History
How it came to be
- Built
- 368–373 CE under Valens; Justinian 576 repairs after Avar cut
- Period
- Late Roman to Ottoman (4th–19th c. CE)
- Culture
- East Roman (Byzantine) Constantinople
- Builders
- Imperial engineers under Valens and prefect Clearchus per Themistius oration
- Purpose
- Water security for Constantinople (500,000 inhabitants) via 426-km Thracian catchment
- Abandoned
- 1453 Ottoman reuse; 1912 still primary Istanbul water; replaced by 20th c. pipes but standing
- Rediscovered
- Always standing; 1912 Crow survey of Thracian lines; 1990s Crow 426-km mapping
- Excavation
- Excavation ongoing
368–373 CE
Valens builds 971-m bridge closing 240-km Thracian system
626 CE
Avars cut aqueduct precipitating siege thirst
1999
J. Crow maps 426-km Thracian network 4th–5th c.
On the ground
Structures & features
41.0160° N · 28.9550° E · 60 m · 3 mapped features
Valens Bridge Central Arch (Atatürk Blvd)
bridge pier26-m tall central pier where boulevard passes through
41.0165° N · 28.9555° EThracian Channel at Cebeciköy
channelUnderground vaulted channel 40 km west showing 0.9 m section
41.1020° N · 28.7850° EKurşunlugerme Siphon Bridge
siphon bridge175-m three-tier siphon bridge 37 m high over Alibey valley 90 km west
41.0800° N · 28.4600° E
Gallery