Kizkulesi is located off the coast of Salacak neighbourhood in Üsküdar district, at the southern entrance of the Bosphorus. It literally means "Maiden's Tower" in Turkish. The name comes from a legend: the Byzantine emperor heard a prophecy telling him that his beloved daughter would die at the age of 18 by a snake. So he decided to put her in this tower built on a rock on the Bosphorus isolated from the land thus no snake could kill her. But she couldn't escape from her destiny, after all, a snake hidden in a fruit basket brought from the city bit the princess and killed her.
Kizkulesi is dating back to the 5th century BC when it was built by the Athenian general Alcibiades on a rock at the entrance of the Bosphorus for the surveillance of the waterway. A chain was pulled from the land to the tower to make it a checkpoint and customs area for the ships going through.
Today, Kizkulesi is a very popular and classy restaurant and cafeteria-bar. It offers 360-degree views of the Bosphorus and the old city, especially at night. There are several shuttle boats going to the tower at certain times from Kabatas neighbourhood on the European side of Istanbul and from Salacak neighbourhood on the Asian side.
http://www.greatistanbul.com/kizkulesi.html