Rumeli Fortress is a large fortress with an area of nearly 16 acres of high walls, towers and green surroundings, located on the European side of Istanbul at the narrowest part of the Bosphorus. It was built over a period of four months in 1452 AD, by the Ottoman Sultan Mehmed II, in preparation for the final attack on Constantinople and the final fall of the Byzantine Empire. It is now one of the most prominent archaeological and tourist attractions in Istanbul and a distinctive destination that attracts large numbers of tourists from all over the world.