Aqueduct of Valens

Interesting facts

In the fourth century Gregory of Nazianzus described the system as a river that ran both beneath the ground and through the air.

Themistius claimed the first channel was 1,000 stadia long; scholars dismissed this as boasting until surveys traced a course that turned out even longer.

After the Avars cut the aqueduct in 626, the city went without its water for more than a century, until Constantine V repaired it following a drought in 758.

Byzantium had an official called the logothete of the waters; one holder, Basil Maleses, was captured by the Seljuks at the Battle of Manzikert in 1071.

The bridge keeps a steady gradient of about one metre in every kilometre, enough to keep the water flowing gently into the city.

The bridge once ran in a straight line, but during the building of the Fatih Mosque it was given a bend in that stretch, for reasons nobody knows.

The upper tier of arches mixes courses of squared stone with layers of Roman concrete, held together by iron clamps.

A popular legend says arches near the Şehzade Mosque were cut to improve the view of it; in fact the 1509 earthquake had brought them down.

In 1912 a stretch of about 50 metres near the Fatih Mosque was demolished, which is why the surviving bridge is shorter than the original.

The Castilian envoy Ruy González de Clavijo, passing through in 1403 on his way to Timur, found the aqueduct still delivering water.

Why it is worth it

The Aqueduct of Valens is the most striking piece of Roman engineering still standing in the middle of Istanbul. Its long double tier of stone and brick arches, known in Turkish as the Bozdoğan Kemeri, strides across the dip between two of the city's hills, the ones now crowned by Istanbul University and the Fatih Mosque, and the traffic of Atatürk Boulevard passes beneath it. The surviving stretch is about 921 metres long and up to about 29 metres high.

It was the final and most visible piece of an enormous water system. Work began under Constantius II and the aqueduct was completed under the Emperor Valens, whose name it bears, with its inauguration recorded in 373. The channels that fed it ran through the hills of Thrace: the first phase alone was some 268 km long, and a fifth-century extension added about 451 km more, reaching springs near Vize, 120 km from the city, which makes it one of the longest water supply systems of the ancient world. The water filled three great open reservoirs and more than a hundred covered cisterns across Constantinople. Tradition says stones from the walls of Chalcedon, demolished after a revolt in 366, went into the arches.

The aqueduct outlived the empire that built it. Byzantine emperors repaired it after the Avars cut it in 626 and after droughts and earthquakes; the Ottomans restored it after the conquest of 1453 to supply their palaces, Suleiman the Magnificent rebuilt a group of arches near the Şehzade Mosque, where the pointed Ottoman arches can still be told apart from the round Roman ones, and Mustafa II restored another five in the 1690s, recording the work in an inscription on the structure. It carried water into the city into modern times. Walking along its foot, you can read those phases in the masonry, layered like the city itself.

Getting there

The aqueduct stands in the Fatih district of central Istanbul, about 0.6 km from the historic centre, spanning Atatürk Boulevard between Saraçhane and the Şehzade Mosque. İstanbul Airport (IST) is about 34 km away; Sabiha Gökçen (SAW) on the Asian side is the city's second airport.

From the encyclopaedia

The Aqueduct of Valens was a Roman aqueduct system built in the late 4th century AD, to supply Constantinople – the capital of the Eastern Roman Empire. Construction of the aqueduct began during the reign of the Roman emperor Constantius II and was completed in 373 by the Emperor Valens. The aqueduct remained in use for many centuries. It was extended and maintained by the Byzantines and the Ottomans.

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Aqueduct of Valens

Interesting facts

Why it is worth it

Getting there

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From the encyclopaedia