In Assassin's Creed Revelations, the historic city called Constantinople during Ezio's journey is Istanbul.
The game is set mainly in Constantinople in 1511, when the city was the capital of the Ottoman Empire. Modern usage identifies the same city as Istanbul. Ezio travels there to pursue keys connected with Altaïr's legacy and to confront the Templar presence operating within the Ottoman political world.
The name distinction reflects historical context rather than two different locations. Constantinople was the traditional name used for the city in the period represented by the game, while Istanbul is its modern official name. The city spans Europe and Asia across the Bosporus, giving Revelations a setting shaped by multiple cultural and political influences.
Revelations was released in 2011 and concludes Ezio's main storyline. It also returns to Altaïr through memory sequences, linking the two major historical protagonists before the series moves to later eras and characters.