In Assassin's Creed Revelations, Constantinople is the principal setting for Ezio's search for Altaïr's secrets.
Ezio travels to Constantinople, the capital of the Byzantine Empire, to find keys connected with Altaïr Ibn-La'Ahad's library in Masyaf. The city's districts, rooftops, markets, and underground passages form the game's main environment. Ezio also becomes involved with the local Assassin faction and the conflict between Byzantines and Ottomans.
The story takes place in the early sixteenth century, when Constantinople was the Ottoman capital. The game includes figures such as Suleiman, the Ottoman prince, and Yusuf Tazim, leader of the Constantinople Assassins. Ezio's missions in the city are interwoven with sequences showing Altaïr's later life.
The modern name Istanbul is often used for the same city, but the game and its historical context chiefly call it Constantinople. Masyaf is the destination tied to the library, not the principal setting of Ezio's search.