Uzun Kemer (Turkish “Long Aqueduct”) is an Ottoman aqueduct bridge on the northern branch of the Kırkçeşme Supply System completed in 1563. It is one of several aqueduct bridges made by Mimar Sinan. A flood in 1563 damaged it, after which it was restored.
Located on the north side of the same branch, it has two tiers of arches, is 25 meters high. It has 50 archers on its upper tier and 47 on its lower tier. Its length is 711 meters, making it the longest aqueduct bridge of the Kırkçeşme Supply System. Traces of an early Byzantine aqueduct suggested that Mimar Sinan built this aqueduct on the foundations on an earlier Byzantine aqueduct.

Sources
The Longest Roman Water Supply Line by Kâzım Çeçen
Sinan’s Water Supply System in Istanbul by Kâzım Çeçen
“The Water Supply of Constantinople 2001-2002” by Richard Bayliss and James Crow
Resources
Aqueducts and Water Supply System of Constantinople Photo Album (Byzantine Legacy Flickr)
Kırkçeşme Water Supply System Photo Album (Byzantine Legacy Flickr)