You may wish to see an introductory page with a map first.
In 1451 the Ottoman possessions included most of the Balkans in Europe
and western and central Anatolia in Asia. The sultans had set their residence in Adrianopolis (Edirne in today's European Turkey, next to the border with Greece and Bulgaria).
The Byzantine Empire was limited to the city of Constantinople and to the despotate of MistrÓ in southern Greece. In that year Sultan Murat died of a stroke and was replaced by his son Mehmet II, a young man of 19. The new sultan was determined to conquer Constantinople overcoming the contrary advice of key members of the Ottoman court.
The castle on the Europe side was the work of Mahomet the
second, before he laid siege to Constantinople: Here, all ships that go to
the Black sea are examined, and mutinous janizaries are often imprisoned, strangled, and thrown into the sea.
Richard Pococke - A Description of the East and Some Other Countries - 1745
Midway of the Bosporus stand two ancient castles, immediately opposite on the narrowest shores. (..) Mohammed II extorted from the ill-fated Constantine Paleologus a permission to found another on the European side, which, extensive as it is, was completed with extraordinary exertion in the space of that year which immediately preceded the fall of the Greek empire. (..) Both these fortresses produce a mean effect in the view, from having sharp roofs instead of battlements; but the site of the Roomily-hissar (European castle) is strikingly grand and romantic.
James Dallaway - Constantinople Ancient and Modern with Excursions to the Shores of the Islands of the Archipelago and to the Troas - 1797
In a few months (in 1452) Mehmet II built a fortress on the European side of the Bosporus, opposite Anadolu Hisar, on a hill controlling a turn of the waterway on the assumed location from which almost 2,000 years before Persian Emperor Darius the Great had watched his army move into Europe.
View from the Bosporus
The Byzantine emperors did not constitute a threat for Mehmet II, but the conquest of Constantinople could lead to a sort of European crusade to defend or regain the city. Mehmet II did not fear so much a by land attack in the Balkans: in 1444 the Ottomans had already defeated at Varna (a port in Bulgaria) a similar attempt by the Hungarians: on that occasion they had been helped by a Genoese fleet to relocate their armies from Anatolia to Varna. Mehmet II was more worried about the Byzantines getting support from Venice and Genoa in response to appeals by the pope. He knew he had to act quickly and that he needed to ensure Genoa would not scuttle his plans: at that time Venice was at war with Milan and also other influential Italian states were involved in this conflict (including the extremely rich Republic of Florence); Mehmet realized it would take some time before the Italians put aside their rivalries (they actually did so when they signed the peace of Lodi in 1454, one year after the fall of Constantinople).
Fatih (the Conqueror) is the title given to Mehmet II in recognition of his conquests and Fatih Bridge is the name given in 1987 to the second bridge which crossed the Bosporus. The bridge is right above the fortress built by Mehmet II.
View of the Bosporus (towards Constantinople)
Constantine XI, the last Byzantine emperor, protested to Mehmet II claiming that the size of the fortress violated the treaties between the two countries: in return Mehmet II charged Constantine with having interfered in dynastic quarrels in the Ottoman ruling family; Mehmet arranged the killing of his own young brother to make sure this would not occur again. In essence the building of Rumeli Hisar was tantamount to a declaration of war: because at that time they fought only during the season of better weather, the actual conflict broke out in the following year: the fateful 1453.
Southern and northern towers
Rumeli Hisar is perhaps the first fortress built in Europe taking into account the use of cannon. From the top of its three octagonal/circular gigantic towers the Ottomans could fire at a great distance, while a battery of cannon right on the edge of the Bosporus could hit at close range any ship attempting to attack the fortress.
Eastern tower and remains of ancient buildings
The three towers were placed inside a curtain of walls which here and there show the use of pieces of columns and of other material taken from ancient buildings.
Sea and mountain gates; the image used as background for this page shows an Ottoman gun inside the fortress
The Genoese too resented Mehmet's decision to build Rumeli Hisar, as they regarded the Bosporus as a strait they controlled (they had acquired from the Byzantines two other fortresses located a few miles north of Rumeli Hisar), but they chose to acquiesce to the violation of treaties and when Mehmet II laid siege to Constantinople they eventually proclaimed the neutrality of their colony in Galata.
Fortresses of the Sultans - Introduction
Fortresses built before 1453:
1 - Anadolu Hisar
2 - Rumeli Hisar
Fortresses built after 1453 and before 1657:
3 - Kale Sultanieh
4 - Kilitbahir
Fortresses built after 1657:
5 - Seddulbahir
6 - Imbro
7 - Tenedo