This tower on an islet at the mouth of the Bosphorus is one of the landmarks of Istanbul. The tower was first built here by Alkibiades in the 6th century BC, and around 350 BC a Macedonian admiral built a splendid mausoleum for his dead wife here.

The French name Tour de Leandre and Turkish name Kizkulesi both originate from legends. According to the first (which was actually set on the Dardanelles rather than the Bosphorus) the mythological hero Leander used to meet here with his beloved Hero, but one night he was drowned while swimming to the Tower and Hero committed suicide. The second refers to a story about a king of Scutari (Uskudar) who kept his beautiful daughter locked up here.

The Byzantine emperor Manuel Comnenus (1143-1180) had towers built both here and at the headland south of the Golden Horn, and chains fixed between the two which prevented ships entering the Bosphorus without permission. Diplomatic talks between the Ottoman Sultan Orhan Gazi (1326-1360) and the Byzantine Emperor Cantakuzenus (1347-1354) are known to have taken place in this tower.

Following the Turkish conquest of Istanbul the tower was used to imprison those being sent into exile. When the wooden tower built in 1726 was destroyed by fire it was replaced by a masonry tower with a lead dome. The present baroque form of this tower dates from repairs carried out in 1830. In the past it served variously as lighthouse, quarantine station, prison and artillery emplacement.