Rumeli Hisar (Rumeli Castle) was built in 1452 by the Ottoman Sultan Mehmed II the Conqueror and has played a historic role in the fact of the conquest of Constantinople that followed the next year. Along with the Anadolu Hisar, was used to control the passage between the Black Sea and Sea of Marmara. The castle is located at the narrowest point of the Bosphorus on the European side of Istanbul and especially in Sarigier below the site of the old Robert College (now University of the Bosphorus).
The construction was completed in June-July 1452 after the winning of two earlier Byzantine towers by Mehmed II, who expanded them within a short time. The layout of the castle has the form of an isosceles triangle. The outer wall thickness of more than one measure, reaching a height of 15 meters. Distinguished three large towers, which bear the names of three commanders of Mehmed II (Tsantarli Halil Pasha, Zaganos Pasha, Pasha Saritza). Its area is estimated to reach the 250 meters along the north-south direction, a width of about 50-100 meters, the highest tower in the southern reaches, just 70 meters above sea level.