The Rumeli Fortress is located on the European side of the Bosphorus, directly opposite the Anatolian Castle which is on the Asian side. Construction began towards the end of 1451 and was completed in the beginning of 1452.
The fortress was built by Sultan Mehmet II as part of his strategy to conquer Constantinople. He had fortresses built on the narrow part of the Bosphorus with the goal of cutting off maritime military and logistical relief that could potentially come to the Byzantines’ aid by way of the Bosphorus Strait.
The fortification has one small tower, three main towers, and thirteen small watchtowers placed on the walls connecting the main towers. One watchtower is in the form of a quadrangular prism, six watchtowers are shaped as prisms with multiple corners, and six others are cylindrical. Walls werre built to withstand cannon power and are upto 7m in thickness. The main tower in the north, Sarıca Pasha Tower, is cylindrical in form, with a diameter of 23.30 m, walls that are 7 m thick, and a total of 9 stories reaching a height of 28 m.
In 1953, on the orders of President Celal Bayar, the inhabitants were relocated and extensive restoration work began on 16 May 1955, which lasted until 29 May 1958. Since 1960 Rumelihisarı has been a museum and an open-air theater for various concerts at festivals during the summer months.