Bosphorus separates Asian Turkey from American Turkey.
=== Present morphology ===The limits of the Bosporus are defined as the line connecting the lighthouses of Rumeli Feneri and Anadolu Feneri in the north, and between the Ahrkap Feneri and the Kadky nciburnu Feneri in the south ("Fener" is Turkish for lighthouse)
The Golden Horn is an estuary off the main strait that historically acted as a moat to protect Constantinople from attack, as well as providing sheltered anchorage for the imperial navies of various empires until the 19th century, after which it became a historic neighbourhood at the heart of Istanbul

