Rumelihisarı or Boğazkesen Fortress is a medieval Ottoman fortress located in Istanbul, Turkey, on a series of hills on the European banks of the Bosphorus. The fortress also lends its name to the immediate neighborhood around it in the city's Sarıyer district.
It was built in 1452 by the order of Fatih Sultan Mehmed, famous as Mehmed the Conqueror or simply Mehmed II, by the narrowest point of the Bosphorus channel.
The building played a role in the Siege and Fall of Constantinople in 1453 and that its very shape and details exemplify the historical developments that led to this world-changing event, the end of the Byzantine Empire after over a thousand years and the establishment of the Ottoman Empire as a major player for five centuries.
