It was to be situated on the narrowest point of the Bosphorus strait, facing another smaller fortress already erected on the Asian side. The construction work finished after 4 months and 19 days. Now it serves as a museum, displaying the canons that were used during the conquest. There is also an outdoor mini-amphitheater used during the various music festivals in Istanbul.
The Rumelihisarı 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. Today, this tower is called the Fatih (Conqueror) Tower after Sultan Mehmed II.
Halil Pasha Tower, a dodecagon prism, which stands at the waterfront in the middle of the fortress. The space within each tower was divided up with wooden floors, each equipped with a furnace. Conical wooden roofs covered with lead crowned the towers.
The fortress had three main gates next to the main towers, one side gate and two secret gates for the arsenal and food cellars next to the southern tower. There were wooden houses for the soldiers and a small mosque, endowed by the Sultan at the time of construction.
The fortress was used as a rather large and impressive Bosphorus toll booth for awhile, then as a barracks, later as a prison, and finally as an open-air theater, but never again as a fortress. Today, the fortress is open to the public as an open-air museum and hosts many concerts and dramatic performances in its amphitheater usually during the summer months.