Rumeli fortress was builtin 1452 by the sultan Mehmet the Conqueror in preparation for the final attack on Constantinople, with the aim to control the sea traffic on the Bosphorus strait and prevent aid from the Black Sea to reach Constantinople during the Turkish siege of the city in 1453, particularly from the Genoese colonies such as Caffa, Sinop and Amasra.

Located at the narrowest section of the Bosphorus Strait it occupies an area of 60.000 m2 (16 acres), had 4 main and 1 smaller gate, and 3 large and 1 smaller tower.