Valens Aqueduct

The Bozdoğan Kemeri was completed in the 370s under the emperor Valens, part of a water system that brought supply into Constantinople from springs well outside the city - the full network ran for hundreds of kilometres and was among the longest built anywhere in the Roman world. What survives in the city is a stretch of about a kilometre of two-tier limestone arches, running between the third and fourth hills, and the striking thing about it now is context: a six-lane boulevard was driven straight under the arches in the twentieth century, so the aqueduct spans moving traffic, with the Süleymaniye behind it on one side and the Fatih district on the other. It stayed in use for water supply well into the Ottoman centuries, repaired repeatedly. There is nothing to enter and no ticket - it is a structure you walk along, photograph from the street, and pass under.

What you actually see

• The double arcade - two tiers of arches in limestone.
• The boulevard beneath - traffic running through the spans.
• The Süleymaniye behind - the mosque on the hill above.
• The repair layers - Ottoman patching visible in the stonework.

When to go

April to June and September to October. Late afternoon light catches the stone; the surrounding streets are quieter at weekends.

Honest expectations

There is no site to visit - it is a monument in a busy road, viewed from pavements with heavy traffic. Ten to thirty minutes covers it.

Nearby

Süleymaniye Mosque is up the hill; Zeyrek and the Fatih mosque complex are west.