Rumelihisarı as seen from the Bosphorus strait. Rumelihisarı (also known as Rumelian Castle and Roumeli Hissar Castle) is a fortress located in the Sarıyer district (but it’s actually close to Bebek), on a hill at the European side of the Bosphorus. It gives the name of the quarter around it. It was built by the Ottoman Sultan Mehmed II between 1451 and 1452, before his army’s conquest of Constantinople.
The castle is situated at the narrowest point with 660 meters of the Bosphorus strait, just opposite of Anadoluhisarı (Anatolian Castle) on the Anatolian side, which is another Ottoman fortress that was built between 1393 and 1394 by Sultan Bayezid I. Photo: wikipedia