Aqueduct of Valens: Roman water conduit to ancient Constantinople.
In its present form, Constantinople's Aqueduct of Valens dates back to 368-375 and is named after the man who was to be defeated and killed in action three years after its completion, in the battle of Adrianople. However, it seems that the emperor Valens only restored an earlier aqueduct, built during the reign of the emperor Hadrian (r.117-138). A second tract was added by Theodosius I; new repairs are recorded during the reign of Justin II.
The largest part of the aqueduct is, of course, a system of subterranean pipes; the arches are only a minor part of it. This part is about 970 meters long, of which 625 have remained intact. It is almost nineteen meters high. The arches bridge the valley between Constantinople's Third and Fourth hills, and bring the water to a cistern built by Theodosius I near Beyazit Square.