The Rumeli Fortress (Rumelihisari) is located on the European side of the Bosphorus. The fortress was built in 1452 to better control the comings and goings in the narrowest point of the strait which spans 660 metres. As ships were obliged to come close to the shore to avoid strong currents, it was the perfect vantage point for this sort of control. Just one year later the fortress was supplanted in importance by two others further up the Bosphorus (at the entrance to the Black Sea ).