Bozdogan arch is one of the oldest water structures of Istanbul. It is also named as Hadrianus or Valens arch. It is construction dates back to the Byzantine era. However, the preciese date of it is construction is not known. The arch built by the Byzantine people in order to provide water to Istanbul was demaged in time.  It was put into service again after the conquest of Istanbul by Fatih Sultan Mehmet. Additions were made to the structure during the rulership of Beyazid II and Kanuni. It is total length was about 1 km. and it is length today is only a few hundred meters. It is protected as it is a historical structure. It is located past the building of Istanbul metropolitan municipality in the the district of Sarachane in Istanbul.Situated between the Fatih and Sehzadebasi districts, this arch was built in 365 AD by the Roman Emperor Valens. It is made of stone and is 592 meters high.