The Bosphorus, called İstanbul Boğazı in Turkish, is the sea channel that runs for about 30 km from the Black Sea down to the Sea of Marmara and cuts İstanbul into a European side and an Asian side. Three suspension bridges and a rail tunnel tie the halves together. On the European shore you pass Dolmabahçe Palace, the Ortaköy Mosque, the fortress of Rumeli Hisarı and the museums of Emirgan and Büyükdere; on the Asian shore, the Maiden's Tower off Salacak, Beylerbeyi Palace, the pavilions of Küçüksu, Çubuklu and Beykoz, and at the Black Sea mouth the castle of Yoros. Each of these places has its own guide on this site.
A strait of bends and two currents
The channel twists through twelve sharp bends, and two currents move in it at once: the fresher water of the Black Sea heads south near the surface, fastest from Kandilli downwards, while the denser, saltier water of the Marmara creeps north along the bed. When a strong southerly wind drives Marmara water into the mouth, a counter-current known as the orkoz can build on top, at times powerful enough to halt the city ferries. Fish migrate through it as well, bonito, bluefish, horse mackerel and tuna above all.
The two shores come nearest each other between Rumelihisarı and Anadoluhisarı, where a fortress guards each bank, and the greatest depth is found off Bebek and Kandilli. Its ancient name, Bosporos, means the ox's passage in Greek, a nod to the myth of Io crossing it as a heifer.
The Bosphorus bridges
Three suspension bridges span the strait, here in the order they were built. The first, completed in 1973 between Ortaköy and Beylerbeyi, was called the Boğaziçi Köprüsü and is now the 15 Temmuz Şehitler Köprüsü. The Fatih Sultan Mehmet Köprüsü followed in 1988, coming down at Rumeli Hisarüstü on the European side and at Kavacık on the Asian. The third, the Yavuz Sultan Selim Köprüsü, links Garipçe in Sarıyer with Poyrazköy in Beykoz. Below the water, trains run through the Marmaray tunnel. The first bridge came at a cost to Beylerbeyi Palace, whose setting it broke up.
Palaces and yalıs
In the eighteenth century the sultan and the court left the historic peninsula for these shores; of their palaces, Dolmabahçe, Çırağan and Beylerbeyi still stand and are the most famous. In between stood the yalıs, timber mansions of the Ottoman elite set right on the water: long houses, mostly of two storeys, with the upper floor jutting over the sea on brackets, the front given to the water and a high wall turned to the lane. On the shores, sultans and statesmen chose Beşiktaş, Ortaköy and Kuruçeşme; Bâbıâli officials, Bebek; non-Muslim families, Arnavutköy; embassies and foreigners kept summer houses at Yeniköy, Tarabya and Büyükdere. Once the First World War was over, many families could not keep their yalıs up, and plenty were sold or lost to fire.
European shore: Dolmabahçe and Ortaköy
Dolmabahçe Palace, in Beşiktaş, stands on the left bank as you come up from the Marmara, looking across at Üsküdar and Kuzguncuk. Its ground was once a bay where the Ottoman fleet anchored, later filled in and made into a garden for the sultans. Abdülmecid wanted one building on a European plan to serve as his home, his summer house, his reception rooms and his government, and Garabet Amira Balyan and his son Nigoğos gave it a sea front 600 metres long. The cost left the treasury paying salaries late, and Abdülmecid lived in it for only five years.
At Ortaköy, on the waterfront, is the Büyük Mecidiye Camii, the mosque everyone calls Ortaköy Camii, which Abdülmecid commissioned from Nigoğos Balyan in 1853. It is walled in white cut stone, with two minarets and a single dome whose walls are pink mosaic; the earthquake of 1894 brought down its fluted minarets, and they were rebuilt plain.
European shore: Rumeli Hisarı to Rumeli Kavağı
Rumeli Hisarı holds the narrowest point, 698 metres across from Anadolu Hisarı on the far bank. Mehmed II raised it in 1452, before the conquest, to stop help reaching the city down the strait from the Black Sea, and the old histories call it Boğazkesen Hisarı. Three pashas each built one of the great towers by the water at their own expense; the Saruca Paşa tower stands twenty-eight metres high, its walls seven metres thick.
At Bebek, an inscription on the church of Aya Haralambos places it on ground that once belonged to the Avars; a plaque of 1830 marks its rebuilding. At Emirgan, the Atlı Köşk, home of the Sakıp Sabancı Museum, was drawn by Edouard De Nari for Prince Mehmed Ali Hasan and finished in 1927, though the prince never lived in it; the house with the horse owes its name to a bronze horse in the garden, cast by Louis Daumas in 1864.
At Büyükdere the Sadberk Hanım Museum opened on 14 October 1980 in the Azeryan Mansion, a three-storey wooden waterside house of the nineteenth century; its collections run from Anatolian archaeology to Ottoman costume and İznik tiles. Near the top of the European shore, Marmaracık Bay Nature Park is a beach and picnic ground in the Mavromoloz woods over Rumeli Kavağı.
Asian shore: the Maiden's Tower and Beylerbeyi
Off Salacak near Üsküdar, where the strait nears the Marmara, the Maiden's Tower, Kız Kulesi, sits on its islet, the only Byzantine work left in Üsküdar. In 1110 the emperor Alexios I put up a wooden tower here inside a stone wall and stretched an iron chain from it to the Mangana quarter on the historical peninsula. The tower fell in the earthquake of 1509, burned in 1721 and was rebuilt for good in stone in 1763, and its lighthouse still blinks at the ships at night.
Beylerbeyi Palace, the summer palace Sarkis Balyan designed for Abdülaziz, rises from the quay in Üsküdar. Work started on 6 August 1863 and the formal opening came on 21 April 1865; on the ground floor, a pool under a glass roof is fed from the sea. Its guests included Eugénie de Montijo, wife of Napoleon III, and the Austro-Hungarian emperor Franz Joseph. Abdülhamid II, brought here from Salonica after the Balkan wars, was kept in the palace under house arrest until his death in 1918.
Asian shore: Küçüksu, Çubuklu and Beykoz
Küçüksu Pavilion sits on the Asian shore between the Göksu and Küçüksu streams. It is a biniş kasrı, a lodge the sultan visited to rest rather than to live in, built for Abdülmecid by Nigoğos Balyan and completed in 1856. Cast-iron railings with a gate on every side surround it instead of high walls, a horseshoe stair of marble climbs the sea front around a fountain pool, and no two fireplaces inside are alike.
At Çubuklu, north of Kanlıca, the Khedive's Villa, Hidiv Kasrı, stands in a wooded park on the slope. Abbas Hilmi Pasha, khedive of Egypt, had Delfo Seminati build it in 1907 in the Art Nouveau manner, with a tower over the strait and a marble fountain beneath a stained-glass ceiling in the entrance; in 1937 his family sold it to the İstanbul municipality.
At Hünkâr İskelesi in Beykoz, Beykoz Mecidiye Pavilion is older than both Dolmabahçe and Beylerbeyi, and the Directorate of National Palaces counts it as the earliest masonry building in the new style on the Bosphorus. Mehmed Ali Pasha of Kavala, governor of Egypt, began it for Abdülmecid in 1845, and his son Said Pasha completed it and handed it over in 1854. After serving as an orphanage and a children's hospital it became a museum in 2017.
Last comes Yoros Castle, also called Anadolukavağı Kalesi, on the eastern side of the Black Sea mouth. With the İmros castle across at Rumeli Kavağı it controlled the way into the strait. Brick lettering in Greek on one of its towers identifies it as Byzantine; the Genoese held it from 1348, and Bayezid I landed here in 1391 and used it as a base before building Anadolu Hisarı.
