Istanbul had been besieged many times before Mehmet the Conqueror took the city in 1453, but it managed to defend itself with the help of the Roman city walls.

During very long sieges, provisions were supplied to the city through sea routes. The Rumeli Fortress was built before the siege in 1453 opposite an earlier Turkish fortress on the other shore to prevent any reinforcements and help to the city from the Black Sea.

The fortress was completed in the amazingly short time of four months in 1452. This largest and strongest fortress of the Middle Ages lost its importance after the fall of the city.

A fine example of classic Turkish military architecture, the fortress adorns the Bosphorus in all its impressiveness.

It was restored in the 1950's and turned into a museum. During the annual Istanbul Festival of Arts, the interior of the fortress is used as an amphitheater. It is best viewed from the Asian shore or from the boats operating on the Bosphorus.